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biliary secretion in elasmobranchs. i. bile collection and composition.bile composition and secretion were studied in tow elasmobranch species, squalus acanthias (spiny dogfish shark) and raja erinacea (small skate), after ligation of the common duct and insertion of cannulas into the gallbladder lumen. fish were then allowed to swim freely in large pools and bile was collected in balloons attached to the externalized cannulas. both species secreted bile for periods of 4-7 days at a maximum rate of 1.77 +/- .89 ml/kg per 24 h in squalus acanthias and 2.66 +/- .89 m ...19764983
scyllo-inositol and myo-inositol levels in tissues of the skate raja erinacea.1. many organs of the skate raja erinacea have been found to contain scyllo-inositol levels that are much higher than myo-inositol, the opposite to that found in mammals. 2. both inositols were found in all skate organs studied. 3. myo-inosose-2 was found to accompany the inositols in many of these organs.1978318234
bilirubin metabolism in the spiny dogfish, squalus acanthias, and the small skate, raja erinacea.1. the main bilirubin conjugate in bile of spiny dogfish (squalus acanthias) and small skate (raja erinacea) is bilirubin monoglucuronide. 2. microsomal preparations from dogfish and small skate liver have similar bilirubin udpglucuronyltransferase (udpgt) activity and catalyze the conjugation of bilirubin with glucose from udpglucose. 3. the activity of bilirubin glucosidation (udpgt) was 0.5 times udpg1t activity in dogfish and 0.15 times in skate liver microsomes. 4. sodium cholate increased ...1977318241
amino acids and cell regulation.free amino play an important role in regulating cell volume in fishes. four tissues/cells (skeletal muscle, rbc, brain, and myocardium) of the little skate, raja erinacea, were selected for detailed study because of their special importance or unique advantage as experimental models. three particular amino acids, beta-alanine, taurine, and sarcosine play a predominant role in all four tissues. as in higher vertebrates, amino acid uptake in skate brain, heart, and rbc is mediated via a na+-depend ...1979395764
cupula motion in the semicircular canal of the skate, raja erinacea. an experimental investigation.an upper bound on the magnitude of semicurcular canal cupula motion was experimentally determined in the isolated labyrinth of the skate, raja erinacea. to visualize the cupula, a glass pipette was pushed through the ampullary wall, and local regions of the cupula were stained by slow infusion of small amounts of alcian blue dye. caloric stimuli which produced large changes in single unit activity in the ampullary nerve and which often recruited several larger, previously silent units were found ...1979463523
comparative aspects of brain barrier systems for nonelectrolytes.blood-brain and blood-csf barriers to inulin were compared in 11 vertebrate species. twenty hours after systemic administration, [14c]inulin penetrated into the central nervous system to an equivalent extent in mudpuppy, salamander (adult and larval), red sculpin, big skate, little skate, southern stingray, and atlantic stingray with values for rb (dpm/g brain divided by dpm/ml plasma) in the range 0.01- 0.04 and for rcsf (dpm/ml csf divided by dpm/ml plasma) from 0.02 to 0.04. these values are ...1978623284
renal tubule ion transport and collecting duct function in the elasmobranch little skate, raja erinacea.renal micropuncture and microdissection techniques with ultramicro fluid analysis have been applied to evaluate single nephron function in the skate, raja erinacea. we have divided the skate nephron into three proximal tubular segments (pts i-iii), three distal coilings (dc i-iii), and a countercurrent loop system located between the proximal segments and the distal coilings. the collecting duct is the principal site of urinary dilution. following exposure of the fish to 75% seawater for about 2 ...1977850120
free amino acids in tissues of the skate raja erinacea and the stingray dasyatis sabina: effects of environmental dilution.concentrations of individual free amino acids were determined in various tissues of the skate (raja erinacea) and the stingray (dasyatis sabina), and the relationship of cellular free amino acid concentrations to intracellular osmoregulation was investigated by adapting these elasmobranchs to half-strength seawater. each tissue characteristically had high levels of certain specific amino acids. skate sing muscle contained high concentrations of sarcosine and beta-alanine, skate heart had high co ...1977850123
two new species of echeneibothrium (cestoda: tetraphyllidea) from skates in the western north atlantic.echeneibothrium bathyphilum sp. n. is described from the deep-sea skate, raja bathyphila holt and byrne. echeneibothrium sobrinum sp. n., a parasite in the spiral intestine of the skates raja ocellata mitchill and raja erinacea mitchill, is described from vineyard sound near woods hole, massachusetts. additional data are given for e. vernetae euzet, 1956, from living and fixed specimens obtained from the type host in the type locality. morphology of the strobilae and bothridia, testes numbers, a ...19751117380
selective hepatic uptake and biliary excretion of 35s-sulfobromophthalein in marine elasmobranchs.the hepatic metabolism of 35s-sulfobromophthalein was studied in the free-swimming elasmobranchs, squalus acanthias (spiny dogfish shark) and raja erinacea (small skate), to evaluate the physiological significance of biliary excretion of organic anions in marine vertebrates. twenty-four hours after intra-arterial injection, 85.8 +/- 15.7% of the administered dose was recovered in bile and liver in dogfish and 78.4 +/- 9.9% in skates. more than 85% of bsp in bile was in unconjugated form in both ...19761248686
intracellular osmoregulatory role of amino acids and urea in marine elasmobranchs.little skates, raja erinacea, and stingrays, dasyatis americana, were gradually transferred over a period of 4-5 days from full strength to approximatley 50% seawater. plasma and muscle osmolarity fell. hematocrits were essentially unchanged. extracellular fluid volume (ecf) of muscle, estimated as the chloride space, increased 70% during this period. regulation of muscle cell volume was associated with sharp declines in cellular concentrations of total amino acids (ninhydrin-positive materials) ...19761267026
comparison of cadmium, mercury and calcium accumulations by isolated hepatocytes of the small skate (raja erinacea) and rat.1. accumulation of calcium, cadmium and mercury by isolated hepatocytes of the small skate (raja erinacea) and rat was examined at 14 and 37 degrees c, respectively. 2. metal uptakes by both species were biphasic, with rat cells accumulating more metal than the skate cells. 3. total accumulation after 30 min was in the order: mercury = cadmium much greater than calcium. 4. in both species calcium and cadmium accumulations were reduced at 4 degrees c, while mercury accumulation was not. 5. cd acc ...19921354142
cadmium inhibits stimulus-response coupling in skate (raja erinacea) electric organ.1. the effects of cadmium on stimulus-response coupling in the skate (raja erinacea) electric organ were examined. 2. cadmium decreased the evoked electrical discharge and the evoked release of 3h-ach in a concentration-related fashion. 3. cadmium (100 microm) also blocked voltage-dependent 45ca uptake. 4. both d-tubocurarine and nifedipine blocked ca uptake and evoked potential, but not 3h-ach release, thus most of the 45ca uptake measured was post-synaptic through l ca channels. 5. nickel, cad ...19921360352
the fine structure of the elasmobranch renal tubule: intermediate, distal, and collecting duct segments of the little skate.sharks, skates, and rays (elasmobranchii) have evolved unique osmoregulatory strategies to survive in marine habitats. these adaptations include a complex renal countercurrent system for urea retention. the fine structure of the complete renal tubular epithelium has yet to be elucidated in any species of cartilagenous fish. the present study, which is a companion to our recent paper describing the ultrastructure of the neck and proximal segments of the elasmobranch nephron, uses thin sections an ...19911781455
isolation of raja erinacea basolateral liver plasma membranes: characterization of lipid composition and fluidity.developing a method for isolating skate (raja erinacea) basolateral liver plasma membranes, as well as characterizing the lipid composition and fluidity of these membranes, was the primary purpose of this study. membranes were isolated using self-generating percoll gradients. marker enzyme studies indicate that this preparation is highly enriched in the basolateral domain of the liver plasma membrane and largely free of contamination by intracellular organelles or canalicular membranes. further, ...19911850780
elasmobranch vision: multimodal integration in the brain.multimodal sensory areas that include vision have been identified physiologically in two separate pallial areas in the telencephalon and in the tectum of the mesencephalon. multisensory integration occurs in the medial pallium of the little skate, raja erinacea, and a primitive squalomorph shark, squalus acanthias, whereas in the advanced galeomorph shark, ginglymostoma cirratum, a major multimodal area is in the dorsal pallium pars centralis. pars centralis has undergone extensive hypertrophy i ...19901982491
immunoglobulin heavy chain gene organization and complexity in the skate, raja erinacea.immunoglobulin heavy chain genes from raja erinacea have been isolated by cross hybridization with probes derived from the immunoglobulin genes of heterodontus francisci (horned shark), a representative of a different elasmobranch order. heavy chain variable (vh), diversity (dh) and joining (jh) segments are linked closely to constant region (ch) exons, as has been described in another elasmobranch. the nucleotide sequence homology of vh gene segments within raja and between different elasmobran ...19902107524
two distinct immunoglobulin heavy chain isotypes in a primitive, cartilaginous fish, raja erinacea.immunoglobulin heavy chain genes in raja erinacea (little skate) are organized in clusters consisting of vh, dh, jh segments and ch exons (1). an immunoglobulin heavy chain mu-like isotype that exhibits 61-91% nucleotide sequence identity in coding segments to the heterodontus francisci (horned shark) mu-type immunoglobulin is described. the overall length of the mu-type clusters is approximately 16 kb; transmembrane exons (tm1 and tm2) are located 3 to ch exon 4 (ch4). in three of four tm-conta ...19902123029
medullary electrosensory processing in the little skate. ii. suppression of self-generated electrosensory interference during respiration.1. previous studies have demonstrated that the resting activity of electrosensory alln fibers is modulated by the animal's own respiratory activity and that all fibers innervating a single ampullary cluster are modulated with the same amplitude and phase relationship to ventilation. we demonstrate that alln fibers in the skate are modulated in this common-mode manner bilaterally, regardless of receptor group, orientation, or position of the receptor pore on the body surface (fig. 2). 2. ascendin ...19902213659
granulated peripolar epithelial cells in the renal corpuscle of marine elasmobranch fish.granulated epithelial cells at the vascular pole of the renal corpuscle, peripolar cells, have been found in the kidneys of five species of elasmobranchs, the little skate (raja erinacea), the smooth dogfish shark (mustelus canis), the atlantic sharpnose shark (rhizoprionodon terraenovae), the scalloped hammerhead shark (sphyrna lewini), and the cow-nosed ray (rhinoptera bonasus). in a sixth elasmobranch, the spiny dogfish shark (squalus acanthias), the peripolar cells could not be identified am ...19892519933
flagellar cells and ciliary cells in the renal tubule of elasmobranchs.flagella or cilia are present on most epithelial cells in the renal tubule of elasmobranch fishes (little skate, spiny dogfish, smooth dogfish, atlantic sharpnose, scalloped hammerhead, cow-nosed ray). flagellar cells, those with numerous flagella ordered in one, two, or more rows on the luminal surface, are shown here for the first time in a vertebrate. the flagellar cells are intercalated among other epithelial cells, each bearing a single cilium, from bowman's capsule to the third subdivision ...19892575649
electrolyte transport by alkaline gland of little skate raja erinacea.transepithelial flux studies and conventional intracellular microelectrode measurements were employed to examine the mechanisms of ion transport by the alkaline gland of the male skate, raja erinacea. these studies reveal that the transepithelial potential is 6.9 +/- 0.6 mv, lumen reference, and that the transepithelial resistance is 140 omega . cm2. the short-circuit current across this epithelium is entirely accounted for by net secretion of cl, whereas transepithelial active transport of na d ...19852579590
a bile alcohol sulfate as a major component in the bile of the small skate (raja erinacea).the nature of bile alcohols and bile acids in gall-bladder and hepatic bile from perfused livers of the small skate (raja erinacea) has been investigated. the main bile alcohol sulfate was isolated by thin-layer chromatography and analyzed by fast atom bombardment mass spectrometry and 13c nmr. following solvolysis and purification on lipidex-deap, the bile alcohol profile was measured by capillary gas-liquid chromatography-electron impact mass spectrometry. based on these studies and on compari ...19892723539
solute effects on mitochondria from an elasmobranch (raja erinacea) and a teleost (pseudopleuronectes americanus).varying osmolarity with sucrose/kcl media resulted in similar effects on the oxidation of glutamate by mitochondria isolated from the livers of an elasmobranch, raja erinacea, and a teleost, pseudopleuronectes americanus. in both species trimethylamine oxide (tmao) inhibited mitochondrial oxidation of glutamate. urea penetrated the inner mitochondrial membrane of both species and equilibrated with a ratio ureai/ureao of unity. urea had little effect on the oxidation of glutamate in both species ...19862876050
renal blood vascular system in the elasmobranch, raja erinacea mitchill, in relation to kidney zones.the arrangement and structure of renal blood vessels were studied in a marine skate with injection of silicone rubber and methacrylate resin after intravenous administration of epinephrine and perfusion fixation. the methacrylate casts were investigated with the scanning electron microscope. histology was performed by light and transmission electron microscopy of serial sections. the course of the blood vessels is described in relation to the renal zones of lateral bundles and mesial tissue. eac ...19883202081
dynamics of skate horizontal cells.the all-rod retina of the skate (raja erinacea or r. oscellata) is known to have the remarkable capability of responding to incremental flashes superimposed on background intensities that initially block all light-evoked responses and are well above the level at which rods saturate in mixed rod/cone retinas. to examine further the unusual properties of the skate visual system, we have analyzed responses of their horizontal cells to intensity-modulated step, sinusoidal, and white-noise stimuli. w ...19883216189
the elasmobranch spiracular organ. i. morphological studies.the spiracular organ is a lateral line derived receptor associated with the first gill cleft (spiracle). its functional morphology was studied in the little skate, raja erinacea, and a shark, the smooth dogfish, mustelus canis, with light and electron microscopy. the spiracular organ is a tube (skate) or pouch (shark) with a single pore opening into the spiracle. the lumen is lined with patches of sensory hair cells, and filled with a gelatinous cupula. in the little skate, hair cells form synap ...19883385671
the elasmobranch spiracular organ. ii. physiological studies.the spiracular sense organs of the little skate, raja erinacea, and the smooth dogfish, mustelus canis, respond to movements of the hyomandibula-cranial joint. afferent activity was recorded from the spiracular organ nerve in isolated preparations consisting of at least part of the cranium, the hyomandibula, and the spiracular organ and nerve. afferents are excited by hyomandibular flexion at its joint with the cranium. single unit recordings in the little skate revealed a single class of units ...19883385672
characteristics of l-alanine uptake in freshly isolated hepatocytes of elasmobranch raja erinacea.the specific transport mechanisms that mediate the hepatic uptake of l-[3h]alanine and of an unnatural homologue, alpha-[14c]methylaminoisobutyric acid (meaib), were analyzed in hepatocyte suspensions from raja erinacea. aminooxyacetate, an inhibitor of aminotransferase activity was used to prevent alanine metabolism. after 3 h of incubation with either 0.5 mm alanine or meaib, hepatic concentrations of these amino acids were significantly higher in the presence than absence of na+ (8 vs. 1 and ...19883364608
cytochrome p-450 isozymes and monooxygenase activity in aquatic animals.the roles of different forms of cytochrome p-450 in activation and deactivation of toxic chemicals, synthesis and breakdown of steroid hormones, and other functions, indicate the significance of these enzymes. monooxygenase systems have been studied in species from several phyla of aquatic organisms. however, cytochrome p-450, the dominant catalyst in xenobiotic monooxygenase activity, is best studied in fish. forms of cytochrome p-450 have been purified from several teleost species, including s ...19873297668
effects of l-alanine on membrane potential, potassium (86rb) permeability and cell volume in hepatocytes from raja erinacea.isolated hepatocytes from the elasmobranch raja erinacea were examined for their regulatory responses to a solute load following electrogenic uptake of l-alanine. the transmembrane potential (vm) was measured with glass microelectrodes filled with 0.5 m kcl (75 to 208 m omega in elasmobranch ringer's solution) and averaged -61 +/- 16 mv (s.d.; n = 68). l-alanine decreased (depolarized) vm by 7 +/- 3 and 18 +/- 2 mv at concentrations of 1 and 10 mm, respectively. vm did not repolarize to control ...19883207743
intracellular signals and volume regulatory response in skate erythrocytes.the volume regulatory response of erythrocytes (rbcs) of the little skate raja erinacea subjected to 30% dilution of their medium is mimicked by the application of phorbol ester or calcium ionophore, implicating protein kinase c and phosphoinositide metabolism in that response. to investigate the signaling link between dilution of the medium and cell response, we measured levels of inositol phosphates (associated with intracellular calcium release) and of diacylglycerol (the physiological activa ...19883202230
the excretion pattern of biliverdin and bilirubin in bile of the small skate (raja erinacea).bile pigment composition (biliverdin, bilirubin and their conjugates) was analyzed in stored gallbladder bile and newly synthesized hepatic bile from the small skate (raja erinacea). during a five day period of captivity, gallbladder volume remained relatively constant while bilirubin and biliverdin content increased two to three fold. biliverdin which accounted for 50% of the pigments did not increase as a percentage of tetrapyrroles during this period. the relative proportion of bilirubin and ...19873571566
behavior of extracellular k+ and ph in skate (raja erinacea) cerebellum.ion-selective microelectrodes were used to measure extracellular k+ concentrations ([k+]o) and extracellular ph (pho) in skate cerebellum under resting and stimulated conditions. consistent with earlier ion analysis of elasmobranch cerebrospinal fluid (csf), [k+]o was 3.6 +/- 0.1 mm. during parallel fiber activation, [k+]o increased to an upper limit of 12-14 mm with an approximately linear dependence on stimulation frequency (1-20 hz). post-stimulus undershoots of 0.1-0.6 mm were seen throughou ...19883179721
chemical and morphological differences in the kidney zones of the elasmobranch, raja erinacea mitch.the histological investigation of the kidney of the skate raja erinacea revealed a thin cap of dorsal bundles, which contain segments of single nephrons that are arranged separately in a countercurrent manner, and a large ventral zone, where the second proximal segments (pii) and parts of the lower nephron are located. this zonation is apparent in fresh, unfixed material and makes it possible to separate small tissue samples under a dissecting microscope. the osmolality in both zones does not di ...19862874934
retinal neurochemistry of three elasmobranch species: an immunohistochemical approach.we surveyed retinas of raja erinacea, mustelus canis, and squalus acanthias for neurotransmitter substances by using antisera directed against the substances themselves or against their synthesizing enzymes. both the peroxidase-antiperoxidase (pap) and indirect fluorescent techniques were employed to visualize the primary antisera. in all three species positive results were obtained with antisera directed against tyrosine hydroxylase (toh), glutamic acid decarboxylase (gad), serotonin (5-ht), an ...19862869065
altered plasma membrane ion permeability in mercury-induced cell injury: studies in hepatocytes of elasmobranch raja erinacea.the effects of hgcl2, ch3hgcl, p-chloromercuribenzene sulfonate (pcmbs), and cdcl2 on plasma membrane and cell metabolic functions of skate (raja erinacea) hepatocytes in suspension culture were assessed by measuring (a) the rates of na+-dependent and -independent l-[14c]alanine uptake, (b) na+-dependent 86rb+ uptake, a measure of na-k-atpase activity, (c) 86rb+ efflux, a measure of k+ permeability, (d) the difference between the 3h2o and [14c]inulin distribution spaces, a measure of intracellul ...19882844008
the presence of a juxtaglomerular apparatus in elasmobranch fish.previous studies have concluded that a juxtaglomerular apparatus evolved in phylogenetic groups "higher" than elasmobranch fishes. the present study shows for the first time a distinct juxtaglomerular apparatus in four marine elasmobranchs, the spiny dogfish squalus acanthias), the smooth dogfish (mustelus canis), the little skate (raja erinacea), and the cownose ray (rhinoptera bonasus). serial semithin sections of these fishes' kidneys reveal the four morphological components of a juxtaglomeru ...19902268068
medullary electrosensory processing in the little skate. i. response characteristics of neurons in the dorsal octavolateralis nucleus.1. ampullary electroreceptors in elasmobranchs are innervated by fibers of the alln, which projects to the dorsal octavolateralis nucleus (don). the purpose of this study is to examine the response characteristics of alln fibers and don neurons to weak d.c. and sinusoidal electric field stimuli presented as local dipole fields. 2. alln fibers respond to presentation of d.c. fields with a phasic burst, followed by a more slowly adapting period of firing. ascending efferent neurons (aens) in the d ...19902213658
cell volume regulation by skate erythrocytes: role of potassium.the role of k transport during cell volume regulation in response to extracellular osmolality, protein kinase c activation, and cellular ca was examined in skate (raja erinacea) red blood cells (rbc). reduction of medium osmolality from 960 to 660 mosmol/kgh2o had no effect on k uptake or efflux despite a 25% increase in cell volume. further reduction to 460 mosmol/kgh2o caused k uptake to double and k efflux to triple resulting in net k loss. net k efflux in 460 mosmol/kgh2o medium was correlat ...19902110786
relaxin from an oviparous species, the skate (raja erinacea).an acid-acetone extract prepared from ovaries of the skate, raja erinacea, contained a weakly crossreacting molecule when tested in a pig relaxin radioimmunoassay. the material was isolated and purified to homogeneity by ion exchange chromatography, molecular exclusion chromatography, and hplc. analytical tests proved the molecule to consist of two chains and to have a molecular weight of 7,500. sequence analyses of the a and b chains yielded the following sequence: glu-glu-lys-met-gly-phe-ala-l ...19873827922
volume-activated taurine efflux from skate erythrocytes: possible band 3 involvement.in a previous study (l. goldstein, s.r. brill, and e.v. freund, j. exp. zool. 254: 114-118, 1990) it was suggested that volume-activated (va) taurine efflux from skate (raja erinacea) erythrocytes might involve the anion exchanger band 3. the aim of the present study was to obtain further evidence for (or against) this possibility. we found that in addition to stilbene disulfonates, two other band 3 inhibitors, n-(azido-2-nitrophenyl)-2-amino sulfonic acid (nap)-taurine and niflumic acid, also i ...19912035694
mechanism of mercurial inhibition of sodium-coupled alanine uptake in liver plasma membrane vesicles from raja erinacea.in mammalian hepatocytes the l-alanine carrier contains a sulfhydryl group that is essential for its activity and is inhibited by mercurials. in hepatocytes of the evolutionarily primitive little skate (raja erinacea), hgcl2 inhibits na(+)-dependent alanine uptake and na+/k(+)-atpase and increase k+ permeability. to distinguish between direct effects of hgcl2 on the na(+)-alanine cotransporter and indirect effects on membrane permeability, [3h]alanine transport was studied in plasma membrane ves ...19911994517
effects of glycine and gaba on the ganglion cels of the retina of the skate raja erinacea.application of glycine and gaba caused inhibition of light-evoked activity from different populations of 'on' center ganglion cells in the retina of the skate (raja erinacea). cells affected by glycine were not affected by gaba and vice-versa. addition of 100 microm strychnine to the glycine-containing perfusate caused a resumption in light-evoked responses of the cells. the action of gaba was antagonized by 100 microm bicuculline methochloride, but not by picrotoxin. autoradiography revealed th ...19853995262
multiple site optical recording of transmembrane voltage (msortv), single-unit recordings, and evoked field potentials from the olfactory bulb of skate (raja erinacea).1. multiple site optical recording of transmembrane voltage (msortv), together with conventional extracellular electrophysiological techniques were utilized with in vivo and in vitro preparations of the olfactory bulb of the atlantic skate raja erinacea to analyze electrical activity simultaneously in layers deep to the glomerular layer. 2. in the living animals and the in vitro isolated olfactory bulb, orthodromic stimulation evoked a compound action potential in the olfactory nerve fibers, fol ...19901981575
polarity of hepatic glutathione and glutathione s-conjugate efflux, and intraorgan mercapturic acid formation in the skate.mechanisms of hepatic glutathione and glutathione s-conjugate efflux were investigated in isolated hepatocytes and perfused liver of the little skate (raja erinacea). glutathione was released by isolated skate hepatocytes at a rate of 0.12 +/- 0.03 nmol.hr-1.(mg protein)-1. in the perfused liver, glutathione concentrations in bile were high (approximately 0.7 mm) compared to hepatic tissue levels (0.61 +/- 0.11 mumol.g-1). during the first hour of perfusion, the biliary glutathione excretion rat ...19911958237
the dissociation between renal hco3- reabsorption and h+ secretion in the skate, raja erinacea. 19744204927
barrier membranes at the outer surface of the brain of an elasmobranch, raja erinacea.this report gives the results of the first electron-microscopic examination of the cell layers covering the outer brain surface and the inner surface of the cartilaginous skull in the skate, raja erinacea. the perivascular glial blood-brain barrier--a characteristic of elasmobranchs--extends to the outer surface of the brain. this outer barrier layer is surrounded, in turn, by a subarachnoid compartment (depth: 30-40 microns), containing loose connective tissue and blood vessels; by an arachnoid ...19911913773
taurine transport in skate hepatocytes. ii. volume activation, energy, and sulfhydryl dependence.isolated skate (raja erinacea) hepatocytes swollen in hypotonic media exhibited a regulatory volume decrease (rvd) that was associated with only a small increase in k+ or 86rb+ efflux but a substantial increase in the release of taurine, an amino acid found in high concentrations in skate hepatocytes. taurine efflux was stimulated in media made hypotonic by addition of h2o or removal of nacl, as well as in cells swollen in isotonic media containing rapidly penetrating solutes (202 mm ethylene gl ...19921550235
osmoregulation and urea metabolism in the little skate raja erinacea. 19715545685
comparative benzo[a]pyrene metabolite patterns in fish and rodents.benzo[a]pyrene is converted to 3-hydroxybenzo[a]pyrene, 9-hydroxybenzo[a]pyrene, benzo[a]pyrene-4,5-dihydrodiol, benzo[a]pyrene-7,8-dihydrodiol, benzo[a]pyrene-9,10-dihydrodiol, and benzo[a]pyrene quinones by postmitochondrial supernatant or microsomes in such fish as the rainbow trout, flounder, salmon, mullet, little skate, fundulus grandis, and sea catfish. it is also now well-established that many fish convert benzo[a]pyrene to potent mutagenic metabolites as has been demonstrated with the a ...19846087145
taurine uptake in atrial myocardium by a sodium-dependent beta-amino acid system in the elasmobranch, raja erinacea. 19806108177
hepatic microsomal nadph-cytochrome p-450 reductase from little skate, raja erinacea. comparison of thermolability and other molecular properties with a mammalian enzyme.components of little skate (an elasmobranch) and rabbit hepatic microsomal cytochrome p-450 dependent monooxygenase systems were examined for differences which might explain the decreasing xenobiotic-metabolizing activity of little skate microsomes assayed at temperatures above 30 degrees c. the proportion of saturated fatty acids in microsomal lipids and the habitat temperature are both lower in skate as compared to rabbit, which is consistent with the known adaptive pattern. the more thermolab ...19836411368
beta-alanine transport in the isolated hepatocytes of the elasmobranch raja erinacea.cells were isolated from the liver of the skate and the uptake of beta-alanine followed using [14c]-beta-alanine. the isolated hepatocytes showed good viability, were found to accumulate beta-alanine from the incubation medium, and did so in a manner indicating a transport system involving a saturable carrier. the data for the rate of beta-alanine uptake suggest that this may be a rate-limiting step in the oxidation of the amino acid by the liver. experiments indicated that the transport system ...19846432939
taurine transport in skate hepatocytes. i. uptake and efflux.taurine is an amino sulfonic acid maintained at relatively high concentrations in skate (raja erinacea) hepatocytes (65 mmol/l intracellular water). to identify the transport mechanisms involved in intracellular taurine accumulation, uptake and efflux of [14c]taurine was measured in freshly isolated skate hepatocytes. uptake of 50 microm taurine at 15 degrees c was essentially linear over 3 h when measured in normal elasmobranch ringer, was diminished by replacement of extracellular cl- with no3 ...19921550234
structure and function of the external gill filaments of embryonic skates (raja erinacea).we have investigated structure and function of the external gill filaments, which occur transiently in the embryonic little skate, raja erinacea. approximately 25-30 days after spawning (body mass 0.03-0.05 g) external gill filaments appear as an outgrowth from the caudal side of the gill arches. these filaments are thread-like, each containing one afferent and one efferent blood vessel, and by day 70-75 (body mass 0.4-0.5 g) they reach their maximum size at a length of about 1 cm and a blood ve ...19921518982
identification of vitellogenin in the little skate (raja erinacea).1. vitellogenin was isolated from mature female skates by selective precipitation with mgcl2/edta followed by chromatography on deae-cellulose columns. 2. a single monomer of approximately 205 kda was identified on 6.0% sds-page gels. 3. in addition, isolation of yolk proteins with ammonium sulfate yielded proteins of 94 and 38 kda (putative phosvitins) and putative lipovitellins of ca 105, 91 and 67 kda. 4. in vivo phosphate incorporation in female and male skates implanted with estradiol indic ...19921458843
an electrosensory area in the telencephalon of the little skate, raja erinacea.on the basis of evoked potential and multiple unit responses we identified a pallial electrosensory area that extends throughout the central one-third of the skate telencephalon. this electrosensory area coincides in its mediolateral and rostrocaudal extent with an area of visual responsiveness. throughout the area peak visual activity is 250-500 micrometers superficial to the maximum electrosensory responses. however, both electrosensory and visual areas appear to be located within the same pal ...19846722549
somatotopy within the medullary electrosensory nucleus of the little skate, raja erinacea.the dorsal octavolateral nucleus is the primary electrosensory nucleus in the elasmobranch medulla. we have studied the topographic organization of electrosensory afferent projections within the dorsal nucleus of the little skate, raja erinacea, by anatomical (hrp) and physiological experiments. the electrosensory organs (ampullae of lorenzini) in skates are located in four groups on each side of the body, and each group is innervated by a separate ramus of the anterior lateral line nerve (alln) ...19846736290
biliary secretion in elasmobranchs. ii. hepatic uptake and biliary excretion of organic anions.[35s]bromosulfophthalein ([35c]bsp), [14c]sodium taurocholate ([14c]natc), and 10 mg of unlabeled bsp.and of phenol-3,6-dibromophthalein disulfonate (dbsp) per kilogram body weight were injected in the caudal artery of free-swimming dogfish sharks (squalus acanthias) and small skates (raja erinacea). twenty-four hours later, 85.8 +/- 15.7% of [35s]bsp was recovered in bile and liver in dogfish and 78.4 +/- 9.9% in skates. similar results were obtained for [14c]natc. unlabeled bsp or dbsp (10 mg/ ...19761267029
fine structure of the elasmobranch renal tubule: neck and proximal segments of the little skate.this is the first in a series of studies that examines the renal tubular ultrastructure of elasmobranch fish. each subdivision of the neck segment and proximal segment of the renal tubule of the little skate (raja erinacea) has been investigated using electron microscopy of thin sections and freeze-fracture replicas. flagellar cells, characterized by long, wavy, flagellar ribbons, were observed in both nephron segments. they were found predominantly in the first subdivision of the neck segment, ...19912012002
characterization of a specific estrogen receptor in the oviduct of the little skate, raja erinacea.in this study we report the first estrogen receptor to be characterized in an oviparous elasmobranch. the skate receptor has high affinity for estradiol (kd = 0.7 nm), binds both estradiol and the synthetic estrogen des, and exists in low quantities (50-100 fmol/g oviduct). the receptor displays rapid binding kinetics with half-times of 5 min at 22 degrees and 77 min at 4 degrees. deae-sepharose chromatography reveals one receptor moiety which elutes between 0.13 and 0.14 m kcl. by sucrose gradi ...19911778408
spreading depression in elasmobranch cerebellum.spreading depression (sd) occurs in the cerebellum of an elasmobranch fish, the skate (raja erinacea, raja ocellata). the elasmobranch cerebellum, because of its unique separation of granular form molecular layer, provides an excellent opportunity to study the characteristics of sd in two distinct neuronal populations. both the dc potential shifts and changes in neuronal activity effected by sd were analyzed. the sd dc potential shifts in both layers closely resembled those in mammalian cerebral ...19807407617
the stereoselectivity of four hepatic glutathione s-transferases purified from a marine elasmobranch (raja erinacea) with several k-region polycyclic arene oxide substrates.product analysis by hplc demonstrated that three hepatic cytosolic glutathione s-transferases of little skate (e-2, e-3 and e-4) were highly stereoselective, if not stereospecific, for thiol reaction at the r-configured oxirane carbons of four k-region arene oxides; pyrene 4,5-oxide, (+/-)-benz[a]anthracene 5,6-oxide, (+/-)-benzo[a]pyrene 4,5-oxide and phenanthrene 9,10-oxide. a fourth transferase, e-5, exhibited no stereopreference with pyrene 4,5-oxide or phenanthrene 9,10-oxide. immunological ...19873607067
acid-induced injury in elasmobranch brain.sodium lactate injection into rat brain produces coagulation necrosis consistent with infarction when ph0 is held at less than or equal to 5.30 for 20 min. such injury may result from excessive astroglial acidification. if true, then brain damage from acidosis in elasmobranchs might evolve differently since glial reaction there to another necrotizing injury, exposure to extreme cold, is dissimilar from that seen in mammals. accordingly, ph0 was monitored and sodium lactate (ph 4.00-7.00) injecte ...19883412631
anion transport in basolateral (sinusoidal) liver plasma-membrane vesicles of the little skate (raja erinacea).the mechanism(s) of [35s]sulphate transport was investigated in basolateral liver plasma-membrane vesicles of the little skate elasmobranch, raja erinacea. imposition of an intravesicular alkaline ph gradient (ph 8.0 in/ph 6.0 out) stimulated sulphate uptake 5-10-fold compared with ph-equilibrated (ph 8.0 in = out) conditions and 2-3-fold over equilibrium sulphate uptake (overshoot). this ph-gradient-stimulated sulphate uptake was temperature-dependent, saturable with increasing concentrations o ...19873426551
molecular cloning of the myelin basic proteins in the shark, squalus acanthias, and the ray, raja erinacia.myelin basic proteins (mbps) are a family of alternatively spliced isoforms present in myelin sheaths of most vertebrates. a reverse transcriptase-polymerase chain reaction (rt-pcr) approach was used to clone mbp isoforms in species representing two superorders of elasmobranchs: squalus acanthias, representing squalomorph sharks, and raja erinacia, representing batoidea rays. two products were generated from each species. the larger product encoded a 155 amino acid protein, the same size as mbps ...19937692075
cytoskeletal organization in clusters of isolated polarized skate hepatocytes: structural and functional evidence for microtubule-dependent transcytosis.isolated hepatocytes from the marine vertebrate raja erinacea (the little skate) retain their structural and functional integrity as clusters of cells formed around a single tubular bile canaliculus, and therefore can be used as a model of polarized hepatocytes in situ. in this study we used confocal and conventional epifluorescence microscopy in conjunction with fluorescent markers and immunocytochemistry to examine the structure and function of the cytoskeleton in these cells. actin filaments ...19957722471
taurocholate uptake by isolated skate hepatocytes: effect of albumin.taurocholate transport was analyzed in a well characterized, polarized hepatocyte preparation from the small skate (raja erinacea), an analbuminemic species that does not synthesize bile acids. in addition, the effect of sodium omission, bovine albumin, ovalbumin, and bovine gamma-globulin on the uptake of taurocholate was studied. uptake could be divided into nonsaturable (0.48 pmol x min-1 x mg protein-1. microm-1) and saturable components (km, 32.5 microm and vmax 110 pmol x min-1 x mg protei ...19873565567
the elasmobranch renal corpuscle: fine structure of bowman's capsule and the glomerular capillary wall.the fine structure of the renal corpuscle of the marine elasmobranch fish, the little skate (raja erinacea), and two species of dogfish sharks, the spiny dogfish (squalus acanthias) and the smooth dogfish (mustelus canis), was studied by light microscopy and by transmission (thin sections, freeze-fracture replicas) and scanning electron microscopy. bowman's capsule was lined by ciliated cells, similar to those of the first part of the tubule, at the urinary pole and squamous cells in the zone be ...19873631544
responses to reversed nh3 and nh4+ gradients in a teleost (ictalurus punctatus), an elasmobranch (raja erinacea), and a crustacean (callinectes sapidus):evidence for nh4+/h+ exchange in the teleost and the elasmobranch.ammonia excretion rates of channel catfish, ictalurus punctatus, little skate (raja erinacea), and blue crab (callinectes sapidus) were measured in experimental regimes which permitted simultaneous assessment of the partial pressure gradients for nonionized nh3 and the chemical concentration gradients of nh4+. under conditions of low external ammonia, the average ammonia excretion was +295 microm kg-1 h-1 for catfish, +149 microm kg-1 h-1 for blue crabs, and +59 microm kg-1 h1 for skates with pa ...19863746231
immunoglobulin light chain class multiplicity and alternative organizational forms in early vertebrate phylogeny.the prototypic chondrichthyan immunoglobulin (ig) light chain type (type i) isolated from heterodontus francisci (horned shark) has a clustered organization in which variable (v), joining (j), and constant (c) elements are in relatively close linkage (v-j-c). using a polymerase chain reaction-based approach on a light chain peptide sequence from the holocephalan, hydrolagus colliei (spotted ratfish), it was possible to isolate members of a second light chain gene family. a probe to this light ch ...19948026868
oligomeric forms of skate erythrocyte band 3. effect of volume expansion.volume expansion of little skate (raja erinacea) erythrocytes leads to the formation of oligomeric forms of the band 3 protein. the oligomers are formed following incubation in hypotonic media or inclusion of a permeant solute such as ethylene glycol. oligomers were detected by specifically labeling the skate erythrocyte band 3 homolog with the radiolabeled stilbene [3h]4,4'-diisothiocyano-1,2 diphenylethane-2,2'-disulfonic acid and cross-linking membrane proteins with the homobifunctional agent ...19948051044
characteristics of bile salt uptake into skate hepatocytes.the substrate specificity for the transporter that mediates the hepatic uptake of organic anions in freshly isolated hepatocytes of the elasmobranch little skate (raja erinacea) was determined for bile salts and bile alcohols. the na(+)-independent transport system exhibits a substrate specificity, which is different from the specificity of na(+)-dependent bile salt transport in mammals. unconjugated and conjugated di- and tri-hydroxylated bile salts inhibit uptake of cholyltaurine and cholate c ...19948192655
multiple molecular forms of gonadotropin-releasing hormone in the brain of an elasmobranch: evidence for ir-lamprey gnrh.these studies investigated brains of skate, raja erinacea (order rajiformes, class chondrichthyes), for gonadotropin-releasing hormone (gnrh) peptides by chromatograph and immunoreactivity with region-specific antisera raised against mammalian gnrh and lamprey gnrh. the region-specific antibody to lamprey gnrh-i was produced following conjugation to bovine serum albumin using the bis-diazotized benzidine method. this antibody was characterized by assaying a range of increasing dilutions of the k ...19938234016
osmotic effects on amino acid oxidation in skate liver mitochondria.the mechanism responsible for the osmotic sensitivity of sarcosine oxidation by liver mitochondria from the little skate, raja erinacea mitchill, is examined. assay medium tonicity, rather than a solute effect (urea or trimethylamine oxide), is probably responsible for the inverse relationship between osmolarity and the rate of oxidation of sarcosine by these mitochondria. sarcosine oxidation proceeds through the flavin-linked sarcosine oxidase with the resultant glycine catabolized in the nad-l ...19862428911
expression cloning of a rat liver na(+)-independent organic anion transporter.using expression cloning in xenopus laevis oocytes, we have isolated a cdna encoding a rat liver organic anion-transporting polypeptide (oatp). the cloned oatp mediated na(+)-independent uptake of sulfobromophthalein (bsp) which was cl(-)-dependent in the presence of bovine serum albumin (bsa) at low bsp concentrations (e.g., 2 microm). addition of increasing amounts of bsa had no effects on the maximal velocity of initial bsp uptake, but it increased the km value from 1.5 microm (no bsa) to 24 ...19948278353
determinants of biliary secretion in isolated perfused skate liver.in the isolated perfused liver of the little skate, raja erinacea, bile flow averaged 5.07 +/- 0.58 (mean +/- se) microliters.h-1.g liver-1 in 21 experiments at a perfusion pressure of 5.0 cm ringer compared to 3.79 +/- 0.32 in 38 experiments at 2.5 cm (p less than 0.05). [14c]inulin readily entered skate bile. bile-to-plasma [14c]inulin ratios corrected for delay in transit time, averaged 0.46 +/- 0.07 at 1 h and rose to 0.74 +/- 0.06 by 4 h, although bile flow remained constant. in experiments ...19827065254
control of extracellular ions in skate brain during osmotic disturbances.regulation of brain water and osmolytes in osmotic disturbances has been studied in the little skate, raja erinacea. free-swimming fish were subjected to seawater plus 125 mm nacl (hyperosmotic; these also received 10 ml/kg body wt im 4.19 m nacl in elasmobranch ringer) or to 50% seawater (hyposmotic). at a set time, fish were killed, and blood and brain (telencephalon and medulla) were analyzed. brain water was divided into a cl- and a non-cl- space. responses of water and osmolytes to osmotic ...19836660332
hemodynamic effects on oxygen consumption and bile flow in isolated skate liver.a technique is described for perfusion of livers from the little skate, raja erinacea, in the isolated state at 15 degrees c utilizing a recirculating, well-oxygenated elasmobranch ringer solution. bile flow and oxygen consumption were optimal and remained relatively constant over a 4- to 5-h perfusion at portal vein pressures of 2.5-5.0 cm ringer. at these pressures, bile flow rates were comparable to values previously observed in the free-swimming skate. in contrast to mammalian species, bile ...19827065253
isolation and characterization of a polarized isolated hepatocyte preparation in the skate raja erinacea.hepatocytes of the small skate (raja erinacea) were isolated by collagenase perfusion and evaluated by a variety of functional and morphologic criteria. cell yield was 1.45 x 10(8) +/- 1.3 x 10(7) cells per isolation, and as long as 8 h after isolation 98% of the hepatocytes excluded trypan blue and no leakage of lactate dehydrogenase (ldh) or cell associated potassium could be detected. oxygen consumption averaged 1.6 +/- 0.5 nmol/min/mg cell protein, was not stimulated by 1 mm succinate, and a ...19873585270
swelling-activated anion conductance in skate hepatocytes: regulation by cell cl- and atp.cell swelling activates an outwardly rectifying anion conductance in mammalian cells. the channel responsible for this conductance mediates volume-regulatory efflux of organic osmolytes such as taurine. we observed a similar conductance in hepatocytes from the skate raja erinacea. whole cell cl- conductance was increased > 100-fold by a 2-fold increase in hepatocyte volume. the conductance was outwardly rectifying and had a relative cation permeability of approximately 0.2. cation permeability w ...19968772430
slow biliary elimination of methyl mercury in the marine elasmobranchs, raja erinacea and squalus acanthias.the present study examined the ability of two marine elasmobranchs (raja erinacea, little skate, and squalus acanthias, spiny dogfish shark) to excrete methyl mercury into bile, a major excretory route in mammals. 203hg-labeled methyl mercury chloride was administered via the caudal vein, and bile collected through exteriorized cannulas in the free swimming fish. skates and dogfish sharks excreted only a small fraction of the 203hg into bile over a 3-day period: in the skate, the 3-day cumulativ ...19863764924
disruption of cell volume regulation by mercuric chloride is mediated by an increase in sodium permeability and inhibition of an osmolyte channel in skate hepatocytes.the mechanism by which mercury leads to cell swelling and impairs the normal regulatory volume decrease (rvd) in cells swollen in hypotonic media was examined in hepatocytes isolated from the little skate, raja erinacea, an osmoconforming marine elasmobranch. skate hepatocytes treated with 50 microm hgcl2 in isotonic medium swelled to volumes double those of control cells, and this was associated with an increase in na+ and k+ permeability. the gain in intracellular na+ exceeded the k+ loss by 0 ...19968887458
increased permeability of a glial blood-brain barrier during acute hyperosmotic stress.brain volume is regulated during acute hypernatremia in the little skate, raja erinacea, based on the gain of osmolytes, including sodium, chloride, and potassium [cserr et al., am. j. physiol. 245 (regulatory integrative comp. physiol. 14): r853-r859, 1983]. in this study we show that this volume regulatory response is complete in 35 min and examine the mechanism of sodium influx across the blood-brain barrier over this period. skates have a glial blood-brain barrier. blood-to-brain transfer co ...19863789200
band 3 in cell volume regulation in fish erythrocytes.erythrocytes of the skate (raja erinacea) demonstrate a regulatory volume decrease response when exposed to hypotonic stress by releasing taurine and other organic osmolytes. we review the transport characteristics, physical changes and signaling pathways of a volume-activated osmolyte channel associated with band 3 in skate red blood cells that can be distinguished from anion channels and is separate from the anion exchanger function of band 3.19968960774
the elasmobranch kidney. i. gross anatomy and general distribution of the nephrons.the morphology of the little skate (raja erinacea) and spiny dogfish shark (squalus acanthias) nephron has been investigated in sexually mature females by 1) gross observations of the kidney surfaces, 2) vascular injections, 3) scanning electron microscopy, 4) light microscopy. in the little skate, each nephron is highly complex and begins at the urinary pole of the renal corpuscle, which is located between a thin, dorsal bundle zone and a thicker, ventral sinus zone. the nephron loops back and ...19854073531
two classes of bipolar cell in the retina of the skate raja erinacea.we have used immunoreactions against serotonin and protein kinase c to visualize two distinct classes of bipolar cell in the all-rod retina of the skate, raja erinacea. to enhance the immunoreaction in serotonin-accumulating bipolar cells, prior to fixation, some retinas were incubated in ringer's solution containing serotonin and pargyline. we found the somata of serotonin-accumulating bipolar cells to be located slightly distal to the midline of the inner nuclear layer. with increasing eccentr ...19969013424
distinct but overlapping populations of commissural and gabaergic neurons in the dorsal nucleus of the little skate, raja erinacea.in the little skate, raja erinacea, the electrosensory primary afferents are responsive to electrical potentials created during the animal's own ventilation, while second-order electrosensory cells in the dorsal nucleus of the medulla suppress the responses to ventilatory potentials but retain their extreme sensitivity to important environmental electric signals. previous electrophysiological studies indicate a role for a commissural pathway between the bilateral dorsal nuclei in ventilatory noi ...19979031733
the elasmobranch kidney. ii. sequence and structure of the nephrons.the nephron and collecting ducts of the little skate (raja erinacea) and spiny dogfish shark (squalus acanthias) have been investigated by light microscopy of semi-thin sections. parts of the tubules (collecting ducts and distal segments) were identified after tubular injections with microfil or carbon. the bundle zone was studied in serial sections. in the sinus zone transitions between the different segments were recorded. thus, a complete reconstruction of the nephron, its subdivision into se ...19854083520
molecular cloning of a rod opsin cdna from the skate retina.skates (raja erinacea and r. ocellata) are among the few animals that have an exclusively rod retina. however, skate rods are unusual in that they are capable of adapting to extremely high levels of illumination that initially saturate the rod photocurrent. this adaptive process restores the ability of the visual cells to respond to incremental photic stimuli and enables them to function under ambient conditions that are subserved by the cone mechanism in mixed (rod/cone) retinae. as a first ste ...19979256070
interrenalectomy and hypophysectomy in relation to liver glycogen levels in the skate (raja erinacea). 19695403621
elasmobranch oculomotor organization: anatomical and theoretical aspects of the phylogenetic development of vestibulo-oculomotor connectivity.the oculomotor organization of two elasmobranch species, smooth dogfish (mustelus canis) and little skate (raja erinacea), was studied by investigating the extraocular muscle apparatus and the oculomotor motoneuron distribution. the macroscopic appearance of the eye muscles was similar to any lateral-eyed vertebrate species (e.g., goldfish, rabbit). the size of extraocular muscles was expressed by counting single muscle fibers and comparing cross-sectional areas of the extraocular muscles. there ...19846470223
the hepatic glutathione transferases of the male little skate, raja erinacea.five cytosolic glutathione transferases were isolated from the liver of the male little skate, raja erinacea, a marine elasmobranch. they were designated e-1 through e-5 in order of their elution from a deae-cellulose column with a 0 to 100 mm kcl gradient in 0.01 m tris (ph 8.0). each eluted peak of glutathione transferase activity, after concentration, was applied to an affinity column prepared by reaction of epoxy-activated sepharose 6b with glutathione (gsh). elution of the various glutathio ...19846539176
generation of immunoglobulin light chain gene diversity in raja erinacea is not associated with somatic rearrangement, an exception to a central paradigm of b cell immunity.in all vertebrate species examined to date, rearrangement and somatic modification of gene segmental elements that encode portions of the antigen-combining sites of immunoglobulins are integral components of the generation of antibody diversity. in the phylogenetically primitive cartilaginous fishes, gene segments encoding immunoglobulin heavy and light chain loci are arranged in multiple clusters, in which segmental elements are separated by only 300-400 bp. in some cases, segmental elements ar ...19957790811
a volume-activated taurine channel in skate hepatocytes: membrane polarity and role of intracellular atp.osmoregulation in isolated hepatocytes and perfused livers of the little skate (raja erinacea), an osmoconforming marine elasmobranch, is mediated in part by the uptake or release of the intracellular osmolyte taurine. to further characterize the efflux mechanism, [14c]taurine release and na(+)-independent uptake were assessed after cell swelling in hypotonic media containing 0.1-100 mm taurine. rate coefficients for [14c]taurine uptake (0.016 +/- 0.002 min-1) and efflux (0.015 +/- 0.003 min-1) ...19947521136
atp depletion and inactivation of an atp-sensitive taurine channel by classic ion channel blockers.cell volume regulation in different cell types is mediated in part by plasma membrane channel(s) that allow taurine and other important intracellular organic osmolytes to efflux from the cell. previous studies have demonstrated that intracellular atp is required for activation of a volume-sensitive taurine-permeable channel. the present study examined the relation between cellular atp and adp concentrations and swelling-induced [14c]taurine efflux and anion current (whole-cell patch-clamp) after ...19957565627
volume-activated osmolyte channel in skate erythrocytes: inhibition by pyridoxal derivatives.volume expansion of erythrocytes of little skate, raja erinacea, triggers the opening of an osmolyte channel. we review this transport mechanism and further investigate the channel's physicochemical nature by probing the channel with a series of pyridoxine derivatives in skate rbc as well as in epithelial cells: mdck and c6 glioma cells and in skate hepatocytes. the identity of the transport mechanism (band 3 vs. an anion channel) which mediates the swelling-activated efflux of osmolytes in fish ...19979392866
afferent and efferent connections of the vestibulolateral cerebellum of the little skate, raja erinacea.horseradish peroxidase and cobaltous lysine tracers are used to determine the afferent and efferent projections of the vestibulolateral cerebellum (vll) in the little skate, raja erinacea. the skate vll has separate divisions, pars medialis and pars lateralis, associated with vestibular and lateralis modalities, respectively. the pars medialis has a typical cerebellar structure with molecular and purkinje cell layers and granular areas. in addition to known inputs from eighth nerve vestibular fi ...19873427408
aryl hydrocarbon receptor function in early vertebrates: inducibility of cytochrome p450 1a in agnathan and elasmobranch fish.the mammalian aryl hydrocarbon receptor (ahr) is a ligand-activated transcription factor that controls the expression of cytochrome p450 1a (cyp1a) genes in response to halogenated aromatic hydrocarbons such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (tcdd). the natural ligand and normal physiologic function of this protein are as yet unknown. one approach to understanding ahr function and significance is to determine the evolutionary history of this receptor and of processes such as cyp1a induction ...19989827018
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