Publications
| Title | Abstract | Year Filter | PMID(sorted ascending) Filter |
|---|
| microtubule-associated protein 2 (map2)-immunoreactive neurons in the retina of bufo marinus: colocalisation with tyrosine hydroxylase and serotonin in amacrine cells. | neuron populations in the retina of the toad, bufo marinus, were labelled with a monoclonal antibody raised against microtubule-associated protein 2 (map2). a subpopulation of cones, probably corresponding to the blue-sensitive small single cones, large diameter amacrine cells in the most proximal row of the inner nuclear layer and some large ganglion cells in the ganglion cell layer were labelled. double labelling experiments were carried out to establish the colocalisation of map2 with known p ... | 1992 | 1358449 |
| gaba-like immunoreactive neurons in the retina of bufo marinus: evidence for the presence of gaba-containing ganglion cells. | gamma-aminobutyric acid (gaba)-like immunoreactive (ir) neurons in the retina of the cane toad bufo marinus were revealed using immunohistochemistry on retinal wholemount preparation and sectioned material. gaba-ir neurons included horizontal, bipolar and amacrine cells in the inner nuclear layer and small to medium sized cells in the ganglion cell layer. a few ir axons were seen in the optic fiber layer of the retina. following the injection of the carbocyanine dye, dii into the optic tectum ga ... | 1992 | 1377083 |
| distribution patterns and coexistence of neurohormonal peptides (anp, bnp, npy, sp, cgrp, enkephalins) in chromaffin cells and nerve fibers of the anuran adrenal organ. | immunohistochemical techniques were used to study the adrenal organs of the anuran species rana esculenta, caldula pulchra and bufo marinus with respect to the distribution and coexistence of atrial natriuretic peptide (anp), brain natriuretic peptide (bnp), substance p (sp), calcitonin gene-related peptide (cgrp), neuropeptide y (npy), leu-enkephalin (leu-enk). met-enkephalin-arg-phe (meap) and dynorphin a 1-17 (dyn). antisera against enzymes involved in catecholamine synthesis, i.e., dopamine- ... | 1992 | 1377603 |
| primary sequence and functional expression of a novel ouabain-resistant na,k-atpase. the beta subunit modulates potassium activation of the na,k-pump. | in order to understand the molecular mechanism of ouabain resistance in the toad bufo marinus, na,k-atpase alpha and beta subunits have been cloned and their functional properties tested in the xenopus laevis oocyte expression system. according to sequence comparison between species, alpha 1, beta 1, and beta 3 isoforms were identified in a clonal toad urinary bladder cell line (tbm 18-23). the sequence of the alpha 1 isoform is characterized by two positively charged amino acids (arg, lys) at t ... | 1992 | 1380956 |
| serotonin synthesis and accumulation by neurons of the anuran retina. | serotonin-synthesizing and serotonin-accumulating neurons were studied in the retinas of xenopus laevis and bufo marinus. all previously identified cell types exhibiting serotonin-like immunoreactivity (sli) were labeled by intravitreal injection of 5,7-dihydroxytryptamine (5,7-dht). they included two amacrine cell types (large and small) in both species, and one bipolar cell type in xenopus. incubation of retinas in culture medium in the ambient light reduced sli in amacrine cells and enhanced ... | 1992 | 1390395 |
| posterior lymph heart pressure and rate and lymph flow in the toad bufo marinus in response to hydrated and dehydrated conditions. | posterior lymph heart pressure, rate and flow were measured in chronically cannulated bufo marinus during normal hydrated and dehydrated conditions. a new surgical technique was developed which allowed direct and constant measurement of the functioning of the posterior lymph hearts with minimal disruption to normal lymph drainage. the mean intra-lymph-heart systolic pressure was 2.29 +/- 0.12 kpa for hydrated animals at rest, decreasing to 1.01 +/- 0.10 kpa after 24 h of dehydration. similarly, ... | 1992 | 1402607 |
| acid-base regulation in response to hypercapnia in the lymphatic and circulatory systems of the toad bufo marinus. | 1992 | 1402611 | |
| structure of autonomic neuromuscular junctions in the sinus venosus of the toad. | the structure of cholinergic and adrenergic neuromuscular junctions in the sinus venosus of the toad, bufo marinus, was determined by electron microscopy. from random sections of sinus venosus tissue it appeared that there were variable separations between cholinergic or adrenergic varicosities and the nearest sinus venosus muscle cell. however, when the structure of complete cholinergic and adrenergic varicosities was determined by examining serial electron micrographs, virtually all varicositi ... | 1992 | 1430795 |
| the role of hypoglossal sensory feedback during feeding in the marine toad, bufo marinus. | behavioral observations demonstrate that bilateral deafferentation of the hypoglossal nerves in the marine toad (bufo marinus) prevents mouth opening during feeding. in the present study, we used high-speed videography, electromyography (emg), deafferentation, muscle stimulation, and extracellular recordings from the trigeminal nerve to investigate the mechanism by which sensory feedback from the tongue controls the jaw muscles of toads. our results show that sensory feedback from the tongue ent ... | 1992 | 1431785 |
| insulin and igf1 receptors in a model renal epithelium: receptor localization and characterization. | insulin and igf1 stimulate transepithelial na+ transport in the urinary bladder of the toad bufo marinus, a model renal epithelium. the signal transduction mechanisms for the natriferic action are unknown. ultrastructural techniques were used to localize both receptors and ligands in the epithelium. electron microscopy using gold-labelled anti-insulin or anti-igf1 receptor antibodies demonstrated the majority of the insulin receptors were associated with the basolateral membrane while igf1 recep ... | 1992 | 1445387 |
| neuron-specific enolase-like immunoreactivity in the vertebrate retina: selective labelling of müller cells in anura. | neuron-specific enolase (nse) immunocytochemistry was carried out in retinae of goldfish, axolotl, clawed frog, cane toad, lizard, chick, guinea-pig, rabbit, rat, cat and human. with the exception of anura, strong immunoreactivity was seen in the large ganglion, amacrine cells and horizontal cells of the retina in all of the other species. photoreceptors were found to be labelled in the rat and human retina and only one cone type in rabbit. photoreceptor pedicles and ellipsoids were stained in t ... | 1992 | 1459864 |
| the effect of adenosine on spontaneous and evoked quantal secretion from different release sites of amphibian motor-nerve terminals. | the effects of adenosine on the spontaneous quantal secretion from different release sites along terminal branches of toad (bufo marinus) motor-nerve terminals was studied. terminal branches were visualized using 3,3-diethyloxardicarbocyanine iodide (dioc2(5))-fluorescence to assist in the placement of extracellular electrodes along different release sites of terminal branches. the maximum rate of spontaneous secretions (fe) observed with an extracellular electrode within any 10 microns length o ... | 1992 | 1480323 |
| spatial buffering of extracellular potassium by müller (glial) cells in the toad retina. | we examined the role of müller (glial) cells in buffering light-evoked changes in extracellular k+ concentration, [k+]o, in the isolated retina of the toad, bufo marinus. we found evidence for two opposing müller cell current loops that are generated by a light-evoked increase in [k+]o in the inner plexiform layer. these current loops, which are involved in the generation of the m-wave of the electroretinogram (erg), prevent the accumulation of k+ in the inner plexiform layer by transporting k+ ... | 1992 | 1483500 |
| acid-base-electrolyte balance responses of bufo marinus to aminoglutethimide, corticosterone, and aldosterone during hypercapnia. | experiments were conducted to test the hypothesis that one or more interrenal steroids are active in regulatory responses to respiratory acidosis in the toad, bufo marinus. toads were divided into four experimental groups. the first group received sham injections. the second group received 1-3 mg of aminoglutethimide (ag) every 8 hr. ag inhibits the conversion of cholesterol to pregnenolone, thus inhibiting all steroid hormone synthesis. the third group received ag + 5 micrograms of aldosterone ... | 1992 | 1505725 |
| the generation and changing retinal distribution of displaced amacrine cells in bufo marinus from metamorphosis to adult. | the generation and retinal distribution of displaced amacrine cells (das) were studied from metamorphosis to adult in the cane toad bufo marinus. displaced amacrine cells were identified by inducing chromatolytic changes in ganglion cells (gcs) following optic nerve section. cells that did not chromatolyse in the ganglion cell layer (gcl) of the retina were regarded as das. the number of das increased considerably from an estimated 10,000 at metamorphosis to 211,000 in the adult toad, and was ac ... | 1992 | 1510247 |
| effect of carbenoxolone sodium on steroid-induced sodium transport in the toad bladder: further studies. | the licorice derivative, carbenoxolone sodium, is a potent inhibitor of the enzyme 11 beta-hydroxysteroid dehydrogenase. when this enzyme is suppressed or is absent, endogenous glucocorticoids induce mineralocorticoid-like sodium retention by the kidney. carbenoxolone sodium administered in vivo to an adrenalectomized rat has also recently been shown to enhance the mineralocorticoid response to submaximal concentrations of aldosterone, deoxycorticosterone (doc) and 11-dehydrocorticosterone (comp ... | 1992 | 1525050 |
| haematopoietic malignancies in zoo animals. | myelogenous leukaemia was found in a russell's viper, a honduran milk snake, a marine toad, a byrne's marsupial mouse and an african hedgehog. lymphocytic leukaemia was present in a broad banded copperhead and an indian lion. visceral lymphomatosis was observed in a snowy owl. | 1992 | 1556254 |
| spontaneous chromomycosis in the marine toad (bufo marinus). | post-mortem examinations were performed on two marine toads, one animal showing neurological disorders and the other multifocal dermatitis. in one case, lesions consisted of a severe granulomatous encephalomyelitis and in the other of multiple granulomas in the nasal cavity, lungs, heart, bone marrow, ovaries and skin. histologically, the lesions revealed varying amounts of dark brown fungal elements, predominantly sclerotic bodies indicative of a mycotic infection due to a pigmented fungus. | 1992 | 1556258 |
| functional characteristics of arterial chemoreceptors in an amphibian (bufo marinus). | in order to further describe the functional characteristics of arterial chemoreceptors of anuran amphibians, multi-unit chemoreceptor discharge frequency (mcdf) was recorded from the carotid (n = 23) or aortic nerve (n = 2) of pithed, unidirectionally ventilated toads (bufo marinus). mcdf increased with decreasing pao2: typically, the threshold pao2 lay between 40 and 60 mmhg. the mcdf-pao2 relationship was right-shifted along the pao2 axis by increasing paco2 (n = 5). in three toads, the mcdf-p ... | 2013 | 1626131 |
| retinal projections in the cane toad, bufo marinus. | the location and extent of retinorecipient areas in the cane toad, bufo marinus, were established by anterograde transport of cobaltic-lysine complex from the cut optic nerve. most of the labeled optic axons travelled in the marginal optic tract, while others were in the axial optic tract, and/or the basal optic tract. retinal projections terminated in both contralateral and ipsilateral targets. in addition to the optic tectum, the main visual center, retinorecipient areas included the suprachia ... | 1992 | 1633552 |
| blockage of na+ currents through poorly selective cation channels in the apical membrane of frog skin and toad urinary bladder. | the blockage of na+ movements through the poorly selective cation channels in the apical membrane of frog skin (rana temporaria) and toad urinary bladder (bufo marinus) was investigated with noise, impedance analysis and microelectrode techniques. na+ currents through this pathway were studied with nacl ringer solutions on both sides. after removal of ca2+ and other divalent cations from the mucosal compartment, a considerable part of isc became insensitive to amiloride. in frog skin, the inhibi ... | 1991 | 1649987 |
| position- and fibre type-dependent selectivity by regenerating motor axons in reformation of the topographical projection to the glutaeus muscle in the adult toad (bufo marinus). | the toad glutaeus magnus muscle receives a topographical innervation dependent on the rostrocaudal origins of glutaeus motor axons on the spinal cord. the same projection is re-established in adult animals after cutting the glutaeus muscle nerve and allowing regenerating axons to reinnervate the muscle (brown and everett (1990) j. comp. neurol. 292:363-372). to determine whether the topographically selective reinnervation of the glutaeus muscle comes about because of genuine positional qualities ... | 1991 | 1655833 |
| acid-base regulation in the toad bufo marinus during environmental hypoxia. | gas exchange and the correlated changes in blood and tissue metabolic and acid-base status were investigated during long term exposure of the toad bufo marinus to graded levels of hypoxia. during hypoxia, pco2 values in blood and tissues fell, leading to a transient alkalosis in the extracellular but not in the intracellular space. a reduction in blood perfusion of the skin during hypoxia may explain why pco2 was low in sartorius muscle under normoxia, but approached the pco2 values found in oth ... | 1991 | 1658901 |
| transport-related modulation of the membrane properties of toad urinary bladder epithelium. | impedance analysis and transepithelial electrical measurements were used to assess the effects of the apical membrane na+ channel blocker amiloride and anion replacement on the apical and basolateral membrane conductances and areas of the toad urinary bladder (bufo marinus). mucosal amiloride addition decreased both apical and basolateral membrane conductances (ga and gbl, respectively) with no change in membrane capacitances (ca and cbl). consequently, the specific conductances of these membran ... | 1991 | 1661156 |
| amiloride blockage of na+ channels in amphibian epithelia does not require external ca2+. | noise analysis was used to study the influence of external ca2+ on the blockage of na+ transport by amiloride. experiments were done using frog skin (rana temporaria and rana catesbeiana), toad urinary bladder (bufo marinus) and epithelia of a6 cells. in nondepolarized skins and bladders, removal of ca2+ from the mucosal bath diminished markedly the inhibitory effect of amiloride. ca2+ depletion also gave rise to the appearance of an additional noise component related to cation movement through ... | 1991 | 1664939 |
| effects of putative modulators of relaxation microinjected into intact amphibian smooth muscle cells. | 1. single smooth muscle cells were isolated intact from the stomach of the toad bufo marinus. the relaxation of cells following cessation of electrical stimulation was compared with those relaxed by pressure microinjection of either metal ion chelators or cyclic nucleotides. 2. injection of either a ca2+ chelator or 3',5'-cyclic amp slowed or halted shortening and promoted re-extension of a cell or collapse of membrane evaginations (blebs) in a manner similar to that following cessation of elect ... | 1991 | 1665860 |
| polymorphism in purified guanylate cyclase from vertebrate rod photoreceptors. | guanylate cyclase from rod photoreceptors of amphibian (toad, bufo marinus, and frog, rana catesbeiana) and bovine retinas was solubilized and purified by a single chromatography step on a gtp-agarose column. silver staining of purified amphibian enzymes in sds/polyacrylamide gels disclosed a doublet band (110 and 115 kda), while the bovine enzyme appeared as a singlet band (110 kda). the identification of these guanylate cyclases was confirmed using three chromatography systems with the purifie ... | 1991 | 1675787 |
| tyrosine hydroxylase-immunoreactive elements in the distal retina of bufo marinus: a light and electron microscopic study. | tyrosine hydroxylase-immunoreactive elements in the distal retina of bufo marinus were investigated using light and electron microscopic immunocytochemistry. at the light microscopic level, immunoreactive somas were seen in the proximal part of the inner nuclear layer, and immunoreactive processes projected both to the inner and outer plexiform layers. in some instances stained axon-like processes traveled from the inner plexiform layer, across the inner nuclear layer to the distal retina. immun ... | 1991 | 1686574 |
| probabilistic secretion of quanta from the release sites of nerve terminals in amphibian muscle modulated by seasonal changes. | the number of quanta secreted from release sites along visualized terminal branches at toad (bufo marinus) neuromuscular junctions during different seasons was determined. terminal branches were visualized by prior staining with the fluorescent dye, 3,3'-diethyloxadicarbocyanine iodide (dioc2(5)). the average number of quanta secreted by release sites and recorded with an extracellular electrode was determined at different positions along terminal branches in winter and summer. there was a decre ... | 1991 | 1687704 |
| effects of acetylcholine and substance p on electrical activity of intact toad gastric muscles. | by using isolated gastric muscle cells of bufo marinus, others have studied the mechanism of action of muscarinic agonists and substance p (sp). to compare responses of isolated cells with those of intact muscles, we have studied the effects of acetylcholine (ach) and sp on membrane potentials of circular muscle cells in strips of intact muscle from the toad gastric corpus region. these cells had average resting potentials of -69 +/- 0.7 mv. membrane potential rhythmically depolarized, producing ... | 1990 | 1689118 |
| co-localization of calcitonin gene-related peptide- and substance p-like immunoreactivity in mucosal intra-epithelial nerves in the toad colon. | mucosal intra-epithelial nerve terminals have been found in the colon of the toad, bufo marinus. co-localized in the fibres are calcitonin gene-related peptide (cgrp)-like immunoreactivity (li) and substance p (sp)-li. the intraepithelial nerves are likely to be terminals of primary afferent sensory neurones. fibres with vasoactive intestinal peptide (vip)-li or neuropeptide y (npy)-li also supply the mucosa but do not penetrate the epithelium. | 1990 | 1701868 |
| hyperpolarization-activated cationic channels in smooth muscle cells are stretch sensitive. | the properties of hyperpolarization-activated channels were studied in single smooth muscle cells from the stomach of the toad, bufo marinus, using the patch-clamp technique. in cell-attached patches, inward channel currents were activated by hyperpolarizing pulses from a holding potential of -20 mv to potentials more negative than -60 mv. the activity of the channels increased and their latency of activation decreased as the hyperpolarization was increased. the slope conductance of the channels ... | 1991 | 1707158 |
| multiple types of ca2+ channels in visceral smooth muscle cells. | single-channel currents were recorded from two classes of ca2+ channels in visceral smooth muscle cells isolated from the stomach of the toad, bufo marinus: a class of small-conductance channels (approximately 11 ps) and a class of large-conductance channels (approximately 26 ps). small-conductance channels were present in a majority of patches and gave rise to a slowly inactivating current (t1/2 approximately 250 ms at 0 mv). openings of large-conductance channels could be unequivocally resolve ... | 1991 | 1710335 |
| effect of neuropeptide-y and galanin on autonomic control of heart rate in the toad, bufo marinus. | the effects of neuropeptide-y (npy) and galanin (gal) on the autonomic control of heart rate were investigated in the anaesthetised toad, bufo marinus. both vagosympathetic trunks were sectioned to prevent reflex changes in heart rate, and the cardiac responses to electrical stimulation of either the vagal or sympathetic fibres to the heart assessed. intravenous, bolus doses of 10 or 20 micrograms (2 or 4 nmol) npy and 5 or 10 micrograms (1.5 or 3 nmol) gal caused pronounced pressor responses bu ... | 1991 | 1717535 |
| leptospires isolated from toads and frogs on the island of barbados. | four pathogenic strains of leptospires were isolated from the kidneys of toads (bufo marinus) and seven from frogs (eleutherodactylus johnstonei). isolates from two toads and one frog belonged to serovar bim, the causative agent of most cases of severe leptospirosis on barbados. the other eight strains belonged to a new serovar within the australis serogroup. the name bajan is proposed for this new serovar of leptospira interrogans. | 1991 | 1741925 |
| intracellular ph in the toad bufo marinus following hypercapnia. | we investigated the effects of hypercapnia on intracellular acid-base regulation in brain and liver of the toad bufo marinus l. after 1 h at 5% co2, arterial pco2 increased significantly, from 1.6 +/- 0.04 to 5.7 +/- 0.23 kpa, while brain and liver intracellular ph (phi) decreased significantly. reductions in phi of both tissues were partially compensated by increased levels of bicarbonate. surprisingly, however, compensation was lower than expected in brain and higher than expected in liver. we ... | 1991 | 1757774 |
| functional properties of interphotoreceptor retinoid-binding protein. | it has been hypothesized that interphotoreceptor retinoid-binding protein (irbp) functions as a two-way carrier of retinoid between the retinal pigment epithelium (rpe) and rod photoreceptors in the vertebrate eye. this hypothesis has been tested in recent studies that have employed purified, initially ligand-free, bovine irbp and the "rpe-eyecup" obtained from the toad (bufo marinus) eye. the present experiments further characterize the irbp/rpe-eyecup system with respect to (i) the solubilizat ... | 1991 | 1775528 |
| calcium homeostasis in single intact smooth muscle cells. | we have demonstrated that iso produces part of its negative inotropic action through activation of the plasmalemmal na+/k+ pump, and reduction of [na+]i. this action is mediated by the beta-adrenergic receptor through activation of adenylate cyclase. the reduction of [na+]i is most probably translated to a change in the contractile state of the cell through activation of the na+/ca2+ exchanger. while the exchanger is at equilibrium when the cell is at rest, after iso it would extrude ca2+ at the ... | 1991 | 1803898 |
| m-wave of the toad electroretinogram. | 1. in the retina, two distinct, light-evoked releases of k+ have been described. one takes place in the outer plexiform layer (opl) and is termed the "distal k+ increase." the other takes place in the inner plexiform layer (ipl) and is termed the "proximal k+ increase." although the distal k+ increase generates the electroretinogram (erg) b-wave, the contribution of the much larger proximal k+ increase to the erg is less well understood. in this paper we detail our investigation of the proximal ... | 1991 | 1812226 |
| probabilistic secretion of quanta from nerve terminals in toad (bufo marinus) muscle modulated by adenosine. | 1. a study has been made of the effect of blocking endogenous adenosine on the statistics of quantal secretion at nerve terminals in toad (bufo marinus) muscle during summer and winter. 2. exogenous adenosine (10-50 microm) reduces the mean quantal content of the endplate potential (epp) recorded with an intracellular microelectrode (m) by 36 +/- 6% (mean +/- s.e.m.), independent of the control value of m in both summer and winter. the variance of the epp (s2) was reduced by adenosine in proport ... | 1991 | 1841950 |
| contribution from a ph- and tonicity-sensitive k+ conductance to toad translens short-circuit current. | studies of toad (bufo marinus) lenses mounted in ussing-type chambers revealed that: (1) the translens short-circuit current (isc) across the posterior surface is primarily carried by the movement of na+ from the posterior bathing solution to the lens; (2) across the anterior face the majority of the isc is mediated by ba(2+)-sensitive channels and the remaining current is rapidly reduced by ouabain; (3) most of the anterior k+ conductance is of the tonicity-sensitive, quinidine-inhibitable type ... | 1991 | 1901798 |
| prostaglandin regulation of h+ secretion in amphibian epithelia. | the role of prostaglandins in regulating h+ excretion in amphibian epithelia was investigated. the abdominal skin of the southern leopard frog rana pipiens and the urinary bladder of the toad bufo marinus were used to measure proton excretion across their mucosal surface. prostaglandin f2 alpha (pgf2 alpha) produced a dose-dependent inhibition of h+ excretion across the frog skin. frogs pretreated with ibuprofen (30 mg.kg-1.day-1 for 3 days) showed an enhanced proton excretion similar to that ob ... | 1991 | 1903604 |
| the morphology and distribution of photoreceptors in the retina of bufo marinus. | the number, cell morphology and retinal distribution of rods and cones were determined in the retina of the toad, bufo marinus. adult animals were sacrificed, both eyes were removed and prepared for either tangential section across the outer segments of the photoreceptor layer, or transverse section across the whole retina. cone densities increased from an average of 7000/mm2 in the peripheral to a maximum of 25,000/mm2 in the central retina. the high cone densities extended across the naso-temp ... | 1998 | 1905114 |
| effects of environmental conditions on mitochondrial-rich cell density and chloride transport in toad skin. | chloride flux across amphibian skin is usually passive, yet largely conductive; previous reports have suggested that aldosterone influences this pathway. the conductive cl- pathway and its regulation were examined further, across the abdominal skin of toads (bufo marinus) adapted to various environments. short-circuit current (isc), total conductance (gt) and cl- influx (jcl) were measured in conditions such that there was net cl- movement in absence of na+ transport. in salt-deprived animals co ... | 1991 | 1905398 |
| effects of central and peripheral chemoreceptor stimulation on ventilation in the marine toad, bufo marinus. | the contributions of central and peripheral chemoreceptors to respiratory control in lightly anesthetized bufo marinus, were assessed by measuring the ventilatory responses to unidirectional ventilation (udv) of the lungs at several concentrations of co2 or o2, during intracranial perfusion (icp) with hypercapnic acidic (5% co2, ph 7.2) or hypocapnic alkaline (0% co2, ph 8.3) mock csf solutions. peripheral chemoreceptor stimulation alone (hypoxia or hypercapnia during icp with hypocapnic alkalin ... | 1991 | 1906195 |
| clinostomum attenuatum (digenea) from the eye of bufo marinus. | two specimens of the cane toad, bufo marinus, were found with single worm infestations of the eye. one worm was excysted in the eye chamber, the other still encysted in the choroid layer; both worms were identified as clinostomum attenuatum. this finding is both a new host record and a new site of development for this amphibian parasite. | 1991 | 1907655 |
| a method for the demonstration of nadph-diaphorase activity in anuran species using unfixed retinal wholemounts. | the presence of nadph-diaphorase enzyme has been previously revealed in fixed mammalian retinal tissue (sagar, 1986). fixed retinae of bufo marinus and xenopus laevis failed to yield selective staining when reacted for nadph-diaphorase. satisfactory staining of retinal neurons was attained when the histochemical reaction was carried out in unfixed retinal wholemounts. the applied method included the following steps: 1) dissection of the fresh retina and the separation of the neural retina from a ... | 1991 | 1908262 |
| nadph-diaphorase positive neurons in the retina of bufo marinus: selective staining of bipolar and amacrine cells. | unfixed retinal tissues of adult bufo marinus were reacted for nadph-diaphorase histochemistry that resulted in selective staining of populations of bipolar and amacrine cells. the number of stained bipolar cells in the retina was estimated to be 233,600 +/- 38,900 (mean +/- s.d.). these cells were non-uniformly distributed across the retina with the highest density of 4,308 cells/mm2 along the visual streak decreasing to lowest density of 1,378 cells/mm2 at the dorsal and ventral poles of the r ... | 1991 | 1908263 |
| prolonged depolarization in rods in situ. | intracellular recordings were made from rods in the superfused retina of the marine toad (bufo marinus). it was found that injection of a brief depolarizing current pulse (0.04-1 na) evoked a distinctive, long-lasting response, here called "the prolonged depolarization." the response appears to be regenerative, has a stereotypical waveform, is typically about 6 mv in amplitude and 3 s in duration, and has a relatively long recovery period (10-60 s). as a rule, the response cannot be directly evo ... | 1991 | 1909172 |
| behavioral thermoregulation of the toad, bufo marinus: effects of air humidity. | two experiments were performed. the first tested the hypothesis that the toad, bufo marinus, will select a lower ambient temperature under dry environmental conditions. this behavioral response would reduce evaporative water loss and facilitate survival on land. the second experiment measured the effects of temperature on evaporative water loss. in the first experiment, toads were placed in a thermal gradient (11-40 degrees c) for 3 days. on days 1 and 3, water-filled dishes were placed along th ... | 1991 | 1909745 |
| potassium-evoked responses from the retinal pigment epithelium of the toad bufo marinus. | changes in the apical and basal membrane potentials and the resultant changes in the transepithelial potential were recorded from the isolated retinal pigment epithelium of the toad bufo marinus while the potassium concentration superfusing the apical membrane was changed. lowering apical potassium caused an initial apically-generated hyperpolarization that increased the transepithelial potential which was usually followed by a delayed basally-generated hyperpolarization that decreased the trans ... | 1991 | 1915678 |
| a possible iridovirus in erythrocytes of bufo marinus in costa rica. | icosahedral viral particles were found in the cytoplasm of erythrocytes and splenic reticular cells of a marine toad (bufo marinus) collected from costa rica. capsids had a maximum diameter of 312 nm and a spherical core with biphasic electron density. viruses in erythrocytes were associated with cytoplasmic assembly areas and vacuoles in cytoplasm. nuclei had finely granular material of decreased electron density located centrally, but contained no viral particles. a group of unenveloped viral ... | 1991 | 1920667 |
| retinal distribution of ganglion cells which project to the ipsilateral optic tectum in bufo marinus. | the retinotectal projection in anura is mainly crossed, although a small proportion of optic axons projects to the ipsilateral tectum. using the fluorescent carbocyanide dye, dii, we mapped the retinal topography of ganglion cells which project to the ipsilateral tectum in adult bufo marinus. dii was injected into particular locations in the right tectum. after 10 days survival both the right and the left retinals were wholemounted and the number and retinal position of retrogradely filled gangl ... | 1991 | 1933341 |
| physiological significance of behavioral hypothermia in hypoxic toads (bufo marinus). | we tested the hypotheses that hypoxic toads (bufo marinus) in a thermal gradient would select a lower than normal temperature and that this behavioral response would be beneficial. under normoxic conditions, selected body temperature was 24.2 +/- 3.6 degrees c. when inspired o2 was 10% or less, mean selected temperature decreased to 15.3 +/- 2.4 degrees c. the theoretical advantages of hypoxia-induced hypothermia we tested include (1) a reduction of oxygen uptake (vo2) by a q10 effect; (2) incre ... | 1991 | 1940767 |
| amiloride inhibits the vasopressin-induced increase in epithelial water permeability. | the vasopressin (vp)-induced increase in water permeability in high-resistance, amphibian epithelia is not altered by the abolition of net na+ flux caused by amiloride added to the apical bathing medium. in this work we looked at the effects on water transport of amiloride added to the serosal medium at a concentration (10(-3) m) known to inhibit na+/h+ exchange. in urinary bladders of bufo marinus, amiloride partially blocked the hydrosmotic response to vp. a similar inhibition was found with c ... | 1990 | 1964723 |
| dendritic morphology and retinal distribution of tyrosine hydroxylase-like immunoreactive amacrine cells in bufo marinus. | tyrosine hydroxylase-like immunoreactive (th-ir) amacrine cells (acs) in the retina of metamorphosing and adult bufo marinus were visualized, and their retinal distribution established, using immunohistochemistry on retinal wholemount and sectioned material. the somata of th-ir acs were located in the innermost part of the inner nuclear layer (inl). their dendrites branched predominantly in the scleral sublamina of the inner plexiform layer (ipl), with sparse branching also in the vitreal sublam ... | 1990 | 1971740 |
| an epidemiological study of snake bite envenomation in papua new guinea. | we report a study of 347 patients with snake bite envenomation in papua new guinea. the male: female ratio of the victims was 1.6:1 and their mean age was 24.5 years; 26% were children less than 15 years old. in all cases in which the bite site was known (334) the snake had bitten the extremities of the victim, with 71.3% of these bites being on the ankle or below. the patients came from three regions: urban papua, rural papua and (mostly rural) new guinea. snake bites occurred more frequently d ... | 1991 | 1994203 |
| compensation of progressive hypercapnia in the toad (bufo marinus) and the bullfrog (rana catesbeiana). | toads (bufo marinus l.) and bullfrogs (rana catesbeiana shaw) were subjected to a series of 24 h step increases in aerial co2 (2, 4, 6 and 8%) to assess the degree of extracellular ph compensation at each co2 level and to ascertain the importance of cutaneous ion transport in this process. elevation of plasma [hco3-] occurs during the 24 h period, with the bullfrogs showing a greater ability to compensate at each step. there was no indication that a [hco3-] threshold of 30 mmol l-1 existed in ei ... | 1990 | 2106565 |
| k(+)-evoked müller cell depolarization generates b-wave of electroretinogram in toad retina. | we tested the hypothesis that a light-evoked increase in [k+]o produces a depolarization of the müller cell membrane, which in turn generates the electroretinogram b-wave current. using bufo marinus isolated retinas and k(+)-selective microelectrodes, we recorded two distinct light-evoked increases in extracellular k+ concentration: one in the inner plexiform layer and the other near the outer plexiform layer; the "distal" k+ increase was found over only 10-microns depth and had a maximum amplit ... | 1990 | 2107544 |
| hyperbaric oxygen effect on active na+ transport across isolated toad skin. | the effect of hyperbaric oxygen (hbo) on na+ transport across the isolated toad (bufo marinus) skin was studied by measuring the transepithelial short-circuit current (isc) and resistance (r) at 5, 8, and 10 ata po2 and 15 ata normoxia during steady state conditions. the imposition of 5, 8, and 10 ata po2 for 2 h resulted in 45, 52, and 85% decrease in isc, respectively. this decrease in isc was always accompanied by an increase in r. when amiloride (10(-4) m) was added to the bathing medium, is ... | 1990 | 2107615 |
| morphological classification and retinal distribution of large ganglion cells in the retina of bufo marinus. | the retrograde transport of horseradish peroxidase (hrp) and cobaltic-lysine complex (clc) was used to morphologically characterize large ganglion cells (gcs) and to determine their distribution in retinal wholemounts and in sectioned material in the retina of bufo marinus. large gcs, amounting to about 0.5% of total gc population, were defined to be those with very large dendritic field sizes varying between 0.1 mm2 to 0.6 mm2 and cell soma sizes of between 100 microns 2 to 400 microns 2. these ... | 1990 | 2108873 |
| effect of temperature on cardiac vagal action in the toad bufo marinus. | the effect of temperature on the action of the vagus nerve on the heart was studied in the toad bufo marinus. experiments were performed on two groups of toads, in one the heart was perfused at a constant rate with oxygenated ringer's solution and in the other the circulation was left intact. in all toads there was a linear relationship between pulse interval (pi) and the frequency of vagal stimulation (fv) at any one temperature. the slope of this relationship changed with temperature, the effe ... | 1990 | 2109033 |
| effect of hematocrit on behavioral thermoregulation of the toad bufo marinus. | this study tested the hypothesis that the oxygen capacity of blood, indexed by hematocrit, affects the body temperature (tb) selected by toads (bufo marinus) in a thermal gradient. anesthetized toads (brevital sodium; 40 mg/kg im) were fitted with a cloacal thermistor and femoral artery cannula. after recovery, they were placed in a thermal gradient ranging from approximately 10 to 40 degrees c. tb was measured for 24 h. then 1-2 ml blood were withdrawn and replaced with an equal volume of eithe ... | 1990 | 2109945 |
| evolutionary specificity of hydrins, new hydroosmotic neuropeptides: occurrence of hydrin 2 (vasotocinyl-gly) in the toad bufo marinus but not in the viper vipera aspis. | hydrin 2 (vasotocinyl-gly), a hydroosmotic peptide resulting from differential processing of provasotocin and recently identified in frog neurohypophysis, has been looked for in the pituitary gland of an exotic toad (bufo marinus) and of a reptile (vipera aspis). hydrin 2 has been found in the amphibian but not in the reptile. this result confirms the evolutionary specificity of hydrin 2 that has been identified only in frogs and toads but not in birds and reptiles. occurrence of hydrin 2 is exp ... | 1990 | 2110910 |
| mechanical transients of single toad stomach smooth muscle cells. effects of lowering temperature and extracellular calcium. | smooth muscle's slow, economical contractions may relate to the kinetics of the crossbridge cycle. we characterized the crossbridge cycle in smooth muscle by studying tension recovery in response to a small, rapid length change (i.e., tension transients) in single smooth muscle cells from the toad stomach (bufo marinus). to confirm that these tension transients reflect crossbridge kinetics, we examined the effect of lowering cell temperature on the tension transient time course. once this was co ... | 1990 | 2110967 |
| signal transmission through the dark-adapted retina of the toad (bufo marinus). gain, convergence, and signal/noise. | responses to light were recorded from rods, horizontal cells, and ganglion cells in dark-adapted toad eyecups. sensitivity was defined as response amplitude per isomerization per rod for dim flashes covering the excitatory receptive field centers. both sensitivity and spatial summation were found to increase by one order of magnitude between rods and horizontal cells, and by two orders of magnitude between rods and ganglion cells. recordings from two hyperpolarizing bipolar cells showed a 20 tim ... | 1990 | 2110968 |
| weber and noise adaptation in the retina of the toad bufo marinus. | responses to flashes and steps of light were recorded intracellularly from rods and horizontal cells, and extracellularly from ganglion cells, in toad eyecups which were either dark adapted or exposed to various levels of background light. the average background intensities needed to depress the dark-adapted flash sensitivity by half in the three cell types, determined under identical conditions, were 0.9 rh*s-1 (rods), 0.8 rh*s-1 (horizontal cells), and 0.17 rh*s-1 (ganglion cells), where rh* d ... | 1990 | 2110969 |
| compartmental and topographical specificity of reinnervation of the glutaeus muscle in the adult toad (bufo marinus). | the extent to which the compartmental and topographical innervation patterns were re-established in the mature glutaeus muscle after nerve cut was determined by hrp retrograde labelling procedures and single motor unit glycogen depletion experiments. glutaeus muscle axons normally cluster together along the length of the sciatic nerve and enter the triceps femoris nerve along with axons to the cruralis and tensor fasciae latae muscles. glutaeus axons did not specifically reinnervate the glutaeus ... | 1990 | 2111337 |
| light-induced calcium release and re-uptake in toad rods. | laser micromass analysis was used to investigate the effect of light on the ca content of rod outer segments in the isolated retina and eyecup of the toad, bufo marinus. isolated retinas were incubated in ringer for which most of the ca (normally 97% 40ca) was replaced with 44ca, so that release of internal ca (as 40ca) could be distinguished from the uptake of 44ca from the external medium. continuous illumination produced a decline in outer segment 40ca content. in bright light, the decrease i ... | 1990 | 2115909 |
| interphotoreceptor retinoid-binding protein promotes rhodopsin regeneration in toad photoreceptors. | interphotoreceptor retinoid-binding protein (irbp) has been hypothesized to function as an intercellular shuttle in the vertebrate eye, serving to transport retinoids between the retinal pigment epithelium (rpe) and photoreceptors in the process by which visual pigment is regenerated after photolysis. this hypothesis was tested in preparations utilizing the toad (bufo marinus) eye and purified, initially ligand-free irbp obtained from the bovine eye. rod outer segments (ros) or neural retinas we ... | 1990 | 2118660 |
| the changing distribution of neurons in the inner nuclear layer from metamorphosis to adult: a morphometric analysis of the anuran retina. | the generation and changing distribution of neurons of the inner nuclear layer (inl) in the retina of two anuran species, bufo marinus and xenopus laevis, were studied from metamorphosis to adult. morphometric studies were undertaken at six developmental stages in bufo and four in xenopus. the number and thickness of neurons in the inl were established in 29 predetermined retinal locations from serial sections of the eyes cut vertically or horizontally. the total number of neurons in the inl inc ... | 1990 | 2118741 |
| effects of vagal stimulation and applied acetylcholine on the arrested sinus venosus of the toad. | 1. the effects of vagal stimulation and applied acetylcholine were compared on sinus venosus preparations of the toad, bufo marinus, in which beating had been inhibited by adding the organic calcium antagonist nifedipine. 2. bath-applied acetylcholine and vagal stimulation each caused membrane hyperpolarizations which were abolished by hyoscine. 3. whereas the hyperpolarization that accompanied vagal stimulation was largely unaffected by barium ions, that produced by bath-applied acetylcholine w ... | 1990 | 2120424 |
| a fluorescent analogue of hydrin 1: a new probe for vasotocin receptors. | hydrin 1 is the biosynthetic precursor of vasotocin in xenopus laevis. we have synthesized deamino and fluorescein analogues of hydrin 1 and characterized their physiological action in the urinary bladder of the toad, bufo marinus. 1-deamino-hydrin 1 (d-hydrin) was more potent than vasotocin in stimulating osmotic water flow across intact bladders and more potent than vasotocin in displacing tritium-labeled vasopressin [( 3h]avp) from cell membranes. 1-deamino-[11-lysine (fluorescein)]-hydrin 1 ... | 1990 | 2121046 |
| salmonellas from the cane toad, bufo marinus. | 1990 | 2121128 | |
| slowing of velocity during isotonic shortening in single isolated smooth muscle cells. evidence for an internal load. | in single smooth muscle cells, shortening velocity slows continuously during the course of an isotonic (fixed force) contraction (warshaw, d.m. 1987. j. gen. physiol. 89:771-789). to distinguish among several possible explanations for this slowing, single smooth muscle cells were isolated from the gastric muscularis of the toad (bufo marinus) and attached to an ultrasensitive force transducer and a length displacement device. cells were stimulated electrically and produced maximum stress of 144 ... | 1990 | 2121895 |
| determination of intracellular ph and pco2 after metabolic inhibition by fluoride and nitrilotriacetic acid. | mean intracellular ph (phi) and pco2 (pico2) have been analysed based on ph and total co2 measurements in tissue homogenates. tissues were sampled from undisturbed worms (sipunculus nudus), squid (illex illecebrosus), trout (salmo gairdneri), toads (bufo marinus), and rats. homogenate metabolism was inhibited by the addition of potassium fluoride and nitrilotriacetic acid (nta). model calculations revealed that the influence of dilution, medium buffers, and contamination by extracellular fluids ... | 1990 | 2124717 |
| morphology and distribution of serotonin-like immunoreactive amacrine cells in the retina of bufo marinus. | using an antibody against serotonin (5-hydroxytryptamine, 5-ht), serotonin-like immunoreactive (serotonin-ir) neurons were demonstrated in the retina of adult bufo marinus. all immunoreactive neurons were identified as amacrine cells (acs). the dendrites of serotonin-ir acs branched diffusely and densely throughout all levels of the inner plexiform layer (ipl) of the retina. the great majority of these cell somata were located in the vitread part of the inner nuclear layer (inl) and a few of the ... | 1990 | 2124921 |
| recovery from bleaching in photoreceptors promoted by biotin, pyruvate, and glucose. | in the rods of bufo marinus and other species, bleaching of the rhodopsin in isolated cells leads to a loss of sensitivity and response amplitude and to a shortened response duration. these changes are permanent for cells bathed in ringer's solution. they are due to as yet unknown modulations in the transduction biochemistry. in this paper, we report that these changes can be partly or completely reversed by supplying biotin, pyruvate, and elevated glucose to the rod. the time course of this rev ... | 1990 | 2125464 |
| sympathetic nerve stimulation and applied transmitters on the sinus venosus of the toad. | 1. the effect of sympathetic nerve stimulation on pacemaker cells of the isolated sinus venosus of the toad, bufo marinus, were examined using intracellular recording techniques. 2. train of stimuli applied to the sympathetic outflow led to a two-component increase in heart rate. shortly after the onset of stimulation the rate of discharge of pacemaker action potentials increased. after the end of the train of stimuli, the heart rate fell and then again increased to remain high for several minut ... | 1990 | 2126042 |
| detergent-based isolation of marginal bands of microtubules from nucleated erythrocytes. | we have developed a new, detergent-based method for the isolation of marginal bands (mbs) of microtubules from non-mammalian vertebrate erythrocytes. the critical step in mb isolation is selective removal of the "membrane skeleton" network (ms), within which the mb is enclosed. to test potential ms solubilizing agents systematically, we prepared dogfish (mustelus canis) erythrocyte cytoskeletons in the presence of protease inhibitors and stored them at -20 degrees c in medium containing 50% glyc ... | 1990 | 2127917 |
| lateral diffusion of visual pigments in toad (bufo marinus) rods and in catfish (ictalurus punctatus) cones. | 1. the lateral diffusion coefficient, d, was determined for visual pigments in red rods, green rods and red-sensitive cones with a photon-counting microspectrophotometer. 2. a novel protocol that involved the placement on a photoreceptor of a single micromeasuring/bleaching beam permitted the determination of d of the pigment. 3. demonstration that d for red rods compared very well with values obtained by other workers using other means validated the protocol. 4. applied to green rods, the proto ... | 1990 | 2128335 |
| the effects of aldehydes on the inward rectifier of skeletal muscle fibres from the toad bufo marinus. | a comparative study of the effects of formaldehyde and glutaraldehyde on the inward rectification in skeletal muscle fibre of the toad bufo marinus was made using two different techniques. in whole sartorius muscle fibres formaldehyde produced a transient increase in conductance, followed by a decrease while glutaraldehyde only produced the second effect, with a rather fast time course. in cut end single fibres both aldehydes produced only a reduction of conductance and eventually the abolition ... | 1990 | 2152375 |
| prostaglandins as mediators of acidification in the urinary bladder of bufo marinus. | experiments were performed to determine whether prostaglandins (pg) play a role in h+ and nh4+ excretion in the urinary bladder of bufo marinus. ten paired hemibladders from normal toads were mounted in chambers. one was control and the other hemibladder received pge2 in the serosal medium (10(-5) m). h+ excretion was measured by change in ph in the mucosal fluid and reported in units of nmol (100 mg tissue)-1 (min)-1. nh4+ excretion was measured colorimetrically and reported in the same units. ... | 1990 | 2158109 |
| kinetic analysis of phasic inhibition of neuronal sodium currents by lidocaine and bupivacaine. | phasic ("use-dependent") inhibition of sodium currents by the tertiary amine local anesthetics, lidocaine and bupivacaine, was observed in voltage-clamped node of ranvier of the toad, bufo marinus. local anesthetics were assumed to inhibit sodium channels through occupation of a binding site with 1:1 stoichiometry. a three-parameter empirical model for state-dependent anesthetic binding to the na channel is presented: this model includes two discrete parameters that represent the time integrals ... | 1990 | 2166601 |
| kinetics of local anesthetic inhibition of neuronal sodium currents. ph and hydrophobicity dependence. | this study assesses the importance of local anesthetic charge and hydrophobicity in determining the rates of binding to and dissociation from neuronal na channels. five amide-linked local anesthetics, paired either by similar pka or hydrophobicity, were chosen for study: lidocaine, two tertiary amine lidocaine homologs, a neutral lidocaine homolog, and bupivacaine. voltage-clamped nodes of ranvier from the sciatic nerve of bufo marinus were exposed to anesthetic externally, and use-dependent ("p ... | 1990 | 2166602 |
| evidence for na+/h+ exchange in vertebrate rod photoreceptors. | in this paper, we have documented our investigation of ph regulation in the rod photoreceptor of the toad, bufo marinus. unlike other neural tissues, the retina depends upon aerobic glycolysis to meet its energy requirements. a consequence of its reliance on glycolysis is a large metabolic production of protons (h+) which must be extruded by ph regulating mechanisms. based on the work of previous authors, we propose that rods share these same characteristics with whole retina. our results in rod ... | 1990 | 2167233 |
| detection of n-acetylated forms of beta-endorphin and nonacetylated alpha-msh in the intermediate pituitary of the toad, bufo marinus. | steady-state analysis of the acid extracts of the intermediate pituitary of the toad, bufo marinus, revealed the presence of multiple forms of beta-endorphin and alpha-msh. approximately 98% of the immunoreactive beta-endorphin was n-acetylated. the major form of n-acetylated beta-endorphin, which represented 81.5% of the total beta-endorphin recovered from this tissue, had an apparent molecular weight of 1.2 kda and a net charge of +1 at ph 2.75. approximately 98% of the immunoreactive alpha-ms ... | 1990 | 2172945 |
| response properties of the toad retinal pigment epithelium. | electrophysiologic responses were recorded in vitro from the retina of the toad, bufo marinus. in the isolated retinal pigment epithelium (rpe)-choroid preparation, a decrease in the k+ concentration outside the apical membrane evoked a sequence of trans-epithelial (tep) and membrane potential changes. a hyperpolarization originating at the rpe apical membrane that increased the tep was followed by a delayed hyperpolarization originating at the basal membrane that decreased the tep. this respons ... | 1990 | 2173687 |
| dual regulation of m current in gastric smooth muscle cells: beta-adrenergic-muscarinic antagonism. | the effects of the beta-adrenergic agent isoproterenol on membrane currents were studied in freshly dissociated gastric smooth muscle cells of bufo marinus. voltage-clamp experiments were carried out with patch pipettes in the tight-seal, whole-cell recording mode or with conventional microelectrodes. isoproterenol induced a current identified as m current by the following criteria: the induced current is outward and carried by k+ ions, is suppressed by muscarine or acetylcholine, remains steadi ... | 1990 | 2177185 |
| neurotensin is localized to paracrine cells in the urinary bladder of the turtle, chrysemys picta. | urinary bladder from the painted turtle, chrysemys picta, contains a substantial population of endocrine/paracrine cells scattered through the mucosal epithelium which immunostains using antisera directed toward mammalian neurotensin (nt). radiommunoassay of 0.1 n hcl extracts of chrysemys bladder indicated an immunoreactive nt (int) concentration of 161 +/- 39 pmol/g tissue (n = 9), an amount lower but comparable in magnitude to that found in mucosal scrapings of the intestine (926 +/- 125 pmol ... | 1990 | 2202609 |
| cholinergic agonists suppress a potassium current in freshly dissociated smooth muscle cells of the toad. | single micro-electrode voltage-clamp and current-clamp techniques were used to study cholinergic responses in single freshly isolated gastric smooth muscle cells from the toad bufo marinus. acetylcholine (ach) or muscarine caused membrane depolarization, which sometimes gave rise to action potentials and contractions. the agonist-induced depolarization is due to the suppression of a voltage-dependent k+ conductance, a conclusion based on the following observations. depolarization was accompanied ... | 1985 | 2414443 |
| innervation of the large arteries and heart of the toad (bufo marinus) by adrenergic and peptide-containing neurons. | the innervation of the major arteries and heart of the toad (bufo marinus) was examined by use of glyoxylic acid-induced catecholamine fluorescence and peptide immunohistochemistry. all arteries possessed a moderate to dense plexus of adrenergic axons, which also showed neuropeptide y-like immunoreactivity (npy-li). some adrenergic axons in the intracardiac vagal trunks showed npy-li, but the varicose adrenergic axons innervating the cardiac muscle of the atria and ventricle, and the coronary bl ... | 1986 | 2417719 |
| decline of electrogenic na+/k+ pump activity in rod photoreceptors during maintained illumination. | light-evoked changes in membrane voltage were recorded intracellularly from rod photoreceptors in the isolated retina preparation of the toad, bufo marinus, during superfusion with a solution containing pharmacological agents that blocked voltage-dependent conductances. under these conditions, the amplitude of the hyperpolarizing photoresponse became much greater than under control conditions. the results of several experiments support the conclusion that this increase in photoresponse amplitude ... | 1986 | 2422316 |
| multiple neuropeptides exert a direct effect on the same isolated single smooth muscle cell. | the contractile effect of various neuropeptides was examined by pressure ejecting these agents from a pipette onto single smooth muscle cells freshly dissociated from the stomach of bufo marinus. substance p, cholecystokinin-octapeptide, and bombesin caused contraction, whereas vasoactive intestinal peptide, secretin, and dopamine inhibited acetylcholine-induced contractions. acetylcholine and the three peptides which produced contraction were found in some instances to act on the same cell, sug ... | 1986 | 2422949 |
| mechanism of inhibition by lithium of sodium transport in the toad bladder. | lithium transport across the urinary bladder of bufo marinus has been studied by means of the short-circuit current technique, as well as unidirectional ion flux measurements. exposure to lithium of the epithelial (mucosal) surface of this preparation led to a slow, progressive decrease of ion transport, with increasing discrepancy between short-circuit current and lithium influx; in fact there was still an appreciable lithium influx across bladder exposed to amiloride even though short-circuit ... | 1985 | 2423168 |
| large-conductance ca2+-activated k+ channels in freshly dissociated smooth muscle cells. | freshly dissociated cells from the stomach muscularis of the toad bufo marinus have been employed to carry out a systematic set of electrophysiological studies on the membrane properties of smooth muscle. the existence of ca2+-activated k+ channels became apparent during the first studies under current clamp. in subsequent studies under voltage clamp, a ca2+-activated. tea-sensitive outward current was evident, and it was more than an order of magnitude larger than any other current observed in ... | 1971 | 2427921 |
| a pharmacological and immunohistochemical study of the splanchnic innervation of ileal longitudinal muscle in the toad bufo marinus. | a study was made of the innervation of the longitudinal muscle of the toad ileum with particular emphasis on the splanchnic innervation by non-adrenergic, non-cholinergic (nanc) nerves. nerve fibres containing substance p-like immunoreactivity (sp-li) were observed in the gut wall and in the ileal wall after degenerative section of the splanchnic nerves. incubation overnight in a high concentration of capsaicin (3 x 10(-4) m) caused degeneration of sp-li fibres. no evidence was obtained for ente ... | 1986 | 2431327 |
| synaptic transmission in amphibian retinae during conditions unfavourable for calcium entry into presynaptic terminals. | toad (bufo marinus) retinae were peeled from the pigment epithelium and superfused over the photoreceptor surface with a calcium-poor, cobalt-rich medium. the shape of the electroretinogram indicated that post-synaptic neurones received synaptic input. adding the putative transmitters glutamate and n-acetylhistidine changed the shape of the electroretinogram. the change suggests that an excess of the putative transmitters blocked a component of synaptic transmission that persisted when a retina ... | 1986 | 2432234 |
| identification and characterization of major ionic currents in isolated smooth muscle cells using the voltage-clamp technique. | voltage-clamp experiments were carried out on freshly dissociated single vertebrate smooth muscle cells from the stomach muscularis of bufo marinus. conventional two-microelectrode methodology was used, thus avoiding rapid dialysis of the cytosol. four major phases of current were identified upon voltage jumps from negative holding levels to more positive levels. the first phase of current was an initial, inward current. this current was blocked by external mn2+ and was of the correct magnitude ... | 1987 | 2436142 |
| characterization of calcium-activated potassium channels in single smooth muscle cells using the patch-clamp technique. | single-channel currents were recorded with the patch-clamp technique from freshly dissociated vertebrate smooth muscle cells from the stomach of bufo marinus. of the variety of channels observed, one displayed a large linear conductance of 250 ps (in symmetric 130 mm kcl) which in excised patches was shown to be highly k+ selective. the probability of the channel being open (po) increased when [ca2+]i was elevated and/or when the membrane potential was made more positive. thus, the features of t ... | 1987 | 2436143 |