| transcapillary refill in hemorrhage and shock. | moderate or major hemorrhage leads to diminished cardiac output and to increased total peripheral resistance. these cannot be corrected fully until blood volume is restored, which, in the absence of therapy, requires the movement of fluid and of protein from the interstitium into the capillaries. this movement appears mediated entirely by changes in the starling forces, dominated in the first phase by a fall in capillary hydrostatic pressure, which promotes a rapid shift of protein-free fluid fr ... | 1981 | 7283706 |
| hypoxic vasoconstriction and fluid filtration in pig lungs. | we have studied the effect of hypoxia [inspired partial pressure of o2 (po2) 50 mmhg] on the relationships among pulmonary blood flow, pulmonary arterial pressure, and fluid filtration rates in isolated blood-perfused pig lungs. our results indicate that hypoxia constricted the vasculature in a manner that caused a parallel shift of the pressure-flow curve to higher pressures. during normoxia, filtration rate was zero at flows less than 1.5 1/min but increased with increases in blood flow above ... | 1981 | 7298444 |
| subcutaneous starling forces in the unanaesthetized guinea-pig fetus with indwelling catheters. | we placed capsules in fetal guinea-pigs for measuring the hydrostatic pressure of the interstitial fluid and for collecting samples of interstitial fluid. the vitelline artery and vein were cannulated to measure blood pressures. plasma colloid osmotic pressure (mmhg) and total protein concentration (g/100 ml) were measured in samples taken from other adult and fetal guinea-pigs and were found to be related by colloid osmotic pressure = 0.16 + 2.32 x protein concentration. the colloid osmotic pr ... | 1981 | 7299103 |
| shortening fraction: its dependence on the starling mechanism. | the influence of increasing muscle length (ml) from l0 to 15 to 20% of l0 and calcium concentration (ca2+) from 1.34 to 10 mmol . litre-1 on shortening fraction has been analysed in cat papillary muscles. shortening fraction was calculated by dividing the amount of shortening by the muscle length at which that shortening occurred. when the muscle shortened at contrast total load, increasing muscle length from approximately or equal to l0 to approximately or equal to 15% above l0, increased the s ... | 1981 | 7307033 |
| interstitial fluid volume, colloid osmotic and hydrostatic pressures in rat skeletal muscle. effect of hypoproteinemia. | colloid osmotic pressures in plasma (copp) and interstitial fluid (copi), interstitial fluid pressure (pi) as well as interstitial fluid volume (ifv) was measured in rat skeletal muscle during development of hypoproteinemia. the hypoproteinemia was induced with intraperitoneal injections of aminonucleoside puromucin causing a renal lesion similar to that in human nephrotic syndrome with renal loss of plasma protein and subsequent fall in copp. when copp fell from control values (about 20 mmhg) t ... | 1981 | 7315408 |
| cardiac effects of splanchnic and non-splanchnic blood volume redistribution during aortic occlusions in dogs. | translocation of blood from the lower body dilates the left ventricle during occlusion of the descending thoracic aorta and by increased activation of the frank-starling mechanism, stroke volume is maintained despite raised aortic blood pressure. the contributions from the splanchnic and non-splanchnic blood volumes to the left ventricular dilation were examined by ultrasonic measurements of myocardial chord length (mcl) in atropinized open-chest dogs. end-diastolic mcl rose by 2.5 +/- 0.9% duri ... | 1981 | 7315445 |
| [echocardiographic study of left ventricular performance during sitting bicycle exercise (author's transl)]. | twelve healthy volunteers, mean age 25.4 +/- 4.18 years, performed sitting bicycle ergometer graded exercise to exhaustion. recordings of left ventricular echocardiographic dimension, heart rate, arterial blood pressure, were obtained at rest and at two minutes intervals during exercise and recovery. echocardiographic tracings were digitized and the values of three complexes were combined and means determined for the overall analysis. heart rate increased from 76.92 +/- 15.09 to 154.91 +/- 12.13 ... | 1981 | 7327323 |
| influence of alterations in starling forces on visceral pleural fluid movement. | the influence of alterations in hydrostatic and oncotic pressure gradients on fluid movement across the visceral pleura was examined in 16 spontaneously breathing anesthetized dogs. the left lung was enclosed in a water-impermeable polyethylene membrane, creating a visceral pleural space; visceral fluid movement was determined as the formation or reabsorption of fluid in this space. aortic, pulmonary arterial, right and left atrial, and pleural pressures were monitored; oncotic pressure was calc ... | 1981 | 7327968 |
| pleural liquid pressure over the interlobar mediastinal and diaphragmatic surfaces of the lung. | pleural liquid pressure (pliq) was measured in the interlobar fissures and over the mediastinal apical, cardiac and diaphragmatic surface. when compared to costal values, pliq was more subatmospheric over the cardiac region at all lung heights by about 5 cm h2o so that a costo-hilar gradient down the interlobar fissures of about 0.7 cm h2o/cm was found. no differences were found for other surfaces. cardiac values, unlike costal ones, became more subatmospheric on increasing ventilation and heart ... | 1981 | 7330492 |
| histamine receptors in the bronchial musculature and vasculature of the dog. | participation of histamine h1- and h2-receptors in the bronchial musculature and vasculature of the dog was investigated by using the method for evaluating airway responses. a peristaltic pump and a starling pneumatic resistance were used for a constant pressure perfusion. dogs given 0.1 - 10 micrograms histamine by a close intraarterial injection showed increases in ventilation overflow (bronchoconstriction) and in blood flow (bronchial vasodilatation) in a dose-dependent manner. the bronchocon ... | 1981 | 7334453 |
| effects of active shortening on tension development of rabbit papillary muscle. | duration and intensity of force development have been shown to be less during active muscle shortening than during isometric contraction. the purpose of this study was to compare force developed during controlled shortening with that predicted by the frank-starling relation. paillary muscles from the right ventricles of rabbits were arranged for isometric tension recording, and isometric contractions were recorded at several lengths. the muscles were then permitted to shorten at velocities of 0. ... | 1980 | 7356035 |
| control of fetal cardiac output during changes in blood volume. | changes in cardiac output (qco), heart rate, right atrial pressure, (pra), and mean systemic pressure (pms) in response to blood volume changes were measured in chronically prepared fetal sheep. with a 10% decrease in blood volume, fetal cardiac output, measured with the microsphere technique, decreased significantly from 592 +/- 28 to 471 +/- 32 ml . min-1 . kg-1. heart rate changed little from control animals (163 +/- 5) to those with decreased volume (161 +/- 10 beats/min). right atrial press ... | 1980 | 7356036 |
| mechanism of hemodynamic responses to occlusion of the descending thoracic aorta. | to examine left ventricular responses to aortic occlusion, changes in end-diastolic volume (edv) and end-systolic volume (esv) were estimated by ultrasonic recordings of myocardial distances in atropinized open-chest dogs. during aortic occlusion edv and esv increased equally, systolic left ventricular pressure (lvp) rose by 86 +/- 8 mmhg, and blood flow more than doubled in the superior vena cava and fell by 90% in the inferior vena cava. during combined occlusion of aorta and inferior vena cav ... | 1980 | 7377312 |
| correlation of fluid exchange in the microcirculation and macrocirculation. | accurate, quantitative information relating to hydraulic conductivity (lp) of the capillary wall in any organ of tissue is essential as the first step toward understanding fluid homeostasis. any perturbation which permanently alters fluid balance will ultimately lead to death and destruction of tissues in the living organism. this report summarizes some recent information relating to lp measurements in single capillary and whole organ experiments. it is shown that the single capillary and whole ... | 1982 | 6765283 |
| fat of the wild avian filarial nematode chandlerella quiscali (onchocercidae: filarioidea) in the domestic chicken. | chandlerella quiscali is a filarial nematode parasitizing the brain of the common grackle (quiscalus quiscula versicolor), blue jay (cyanocitta cristata bromia), brown-headed cowbird (molothrus ater ater), and starling (sturnus vulgaris). filarial infections of many wild bird species are common but natural infections of domestic fowl are rare. the habits of many wild birds commonly bring them in close association with domestic poultry. because of the high prevalence of c. quiscali in grackles (9 ... | 1980 | 7393850 |
| the effect of increasing preload on ventricular output and ejection in man. limitations of the frank-starling mechanism. | | 1980 | 7398014 |
| effects of calcium on the sarcomere length-tension relation in rat cardiac muscle. implications for the frank-starling mechanism. | | 1980 | 7408137 |
| proximal reabsorption during metabolic acidosis in the rat. | the mechanism by which proximal volume reabsorption is reduced during hyperchloremic metabolic acidosis was studied using free-flow micropuncture techniques in munich-wistar rats. compared with control hydropenic conditions, absolute rates of proximal total co2 and water reabsorption rates during nh4cl-induced metabolic acidosis were diminished: from 557 +/- 35 to 204 +/- 19 pmol/min and from 13.0 +/- 1.0 to 9.7 +/- 0.6 nl/min, respectively. inhibition of proximal volume reabsorption during meta ... | 1982 | 6805335 |
| hemodynamics in patients with severe toxemia during labor and delivery. | three patients with severe pre-eclampsia-toxemia were studied with thermodilution tip pulmonary artery catheters. all patients were delivered by cesarean section with general anesthesia and endotracheal intubation. the left ventricular stroke work indices (lvswi) of these patients were higher than those of normal nonpregnant subjects. there was no evidence of myocardial depression in terms of either cardiac index or the lvswi-pulmonary capillary wedge pressure (frank-starling) relationship. pulm ... | 1980 | 7416216 |
| an analysis of the mechanical disadvantage of myocardial infarction in the canine left ventricle. | an isotropic, initially spherical, membrane model of the infarcted ventricle satisfactorily predicts ventricular function in the infarcted heart when compared to clinical information and available ventricular models of higher complexity. computations based on finite element solutions of this membrane model yield end-diastolic and end-systolic pressure-volume curves, from which ventricular function curves are calculated, for infarcts of varying size and material properties. these computations ind ... | 1980 | 7418131 |
| comparison between lung fluid filtration rate and measured starling forces after hemorrhagic and endotoxic shock. | the measurement of pulmonary vascular pressure and plasma oncotic pressure (pi p) is reported to be useful for predicting excess fluid transport across the pulmonary microcirculation in the critically ill. however, interpretation of change in these forces must take into consideration the compensatory changes in the other starling forces, particularly interstitial oncotic pressure (pi i) and the permeability characteristics of the membrane. we calculated pulmonary microvascular pressure pmv, pi p ... | 1980 | 7420495 |
| alterations of myocardial function during early stages of mild experimental ischemia in dogs determined by left ventricular pressure-wall thickness loop. | alternations of regional left ventricular myocardial function immediately after coronary artery branch ligation as related to the total left ventricular function were determined by utilizing left ventricular pressure-wall thickness loop in 6 anesthetized open-chest dogs. end-diastolic wall thickness was decreased immediately from 11.54+/-0.50 mm (standard error of the mean) of control to 10.99+/-0.50 mm in 5 to 10 min after ligation (p<0.05), while regional myocardial work calculated as the loop ... | 1980 | 7420735 |
| reversal of ischemic damage with amino acid substrate enhancement during reperfusion. | twenty dogs underwent 15 minutes of normothermic ischemic arrest and 30 minutes of reperfusion while on cardiopulmonary bypass. in 10 control dogs, the reperfusate blood was not modified. in 10 other dogs, the aorta was reclamped and the heart reperfused for 5 minutes with blood containing l-glutamate (0.026m). we measured coronary blood flow (microspheres), left ventricular (lv) metabolism [o2 content, adenosine triphosphate (atp)], lv compliance (intraventricular balloon), and lv performance ( ... | 1980 | 7434210 |
| effect of saline expansion on peritubule capillary pressures and reabsorption. | the effect of extracellular volume expansion on transcapillary starling forces, capillary uptake, and the reabsorption coefficient in the peritubule microcirculation of the dog kidney was examined. micropuncture techniques were used to obtain measurement before and after 4% body wt expansion with isotonic saline. extracellular volume expansion significantly changed all starling pressures and capillary uptake. efferent arteriolar oncotic pressure, interstitial oncotic pressure, and capillary upta ... | 1981 | 7468796 |
| studies of hypoxemic/reoxygenation injury: without aortic clamping. ii. evidence for reoxygenation damage. | this study tested the hypothesis that the developing heart is susceptible to oxygen-mediated damage after reintroduction of molecular oxygen and that this "unintended" reoxygenation injury causes lipid peroxidation and functional depression that may contribute to perioperative cardiac dysfunction. among 49 duroc-yorkshire piglets (2 to 3 weeks old, 3 to 5 kg) 15 control studies were done without hypoxemia to test the effects of the surgical preparation (n = 10) and 60 minutes of cardiopulmonary ... | 1995 | 7475168 |
| studies of hypoxemic/reoxygenation injury: without aortic clamping. iv. role of the iron-catalyzed pathway: deferoxamine. | this study tests the hypothesis that an iron chelator, deferoxamine, can reduce oxygen-mediated myocardial injury and avoid myocardial dysfunction after cardiopulmonary bypass by its action on the iron-catalyzed haber-weiss pathway. twenty-one immature 2- to 3-week-old piglets were placed on cardiopulmonary bypass for 120 minutes, and five piglets served as biochemical controls without cardiopulmonary bypass. five piglets underwent cardiopulmonary bypass without hypoxemia (cardiopulmonary bypass ... | 1995 | 7475170 |
| studies of hypoxemic/reoxygenation injury: without aortic clamping. ix. importance of avoiding perioperative hyperoxemia in the setting of previous cyanosis. | this study of an in vivo infantile piglet model of compensated hypoxemia tests the hypothesis that reoxygenation on hyperoxemic cardiopulmonary bypass produces oxygen-mediated myocardial injury that can be limited by normoxemic management of cardiopulmonary bypass and the interval after cardiopulmonary bypass. twenty-five immature piglets (< 3 weeks old) were placed on 120 minutes of cardiopulmonary bypass and five piglets served as a biochemical control group without cardiopulmonary bypass. fiv ... | 1995 | 7475175 |
| pressure-flow relationships in in vitro model of compartment syndrome. | compartment syndrome is a condition in which an increase in intramuscular pressure decreases blood flow to skeletal muscle. according to the starling resistor (i.e., vascular waterfall) model of blood flow, the decrease in flow could occur through an increase in arterial resistance (rart) or an increase in the critical closing pressure (pcrit). to determine which explains the decrease in flow, we pump perfused a canine gastrocnemius muscle placed within an airtight box, controlled box pressures ... | 1995 | 7559222 |
| the influence of isotonic exercise on cardiac hypertrophy in arterial hypertension: impact on cardiac function and on the capacity for aerobic work. | intense physical training through isotonic exercises has controversial effects in individuals with moderate to severe hypertension. in this study, normotensive wistar rats and rats with renovascular hypertension (goldblatt ii) were subjected to intense physical exercise involving two 50-min swimming sessions per day for a period of 12 weeks. at the end of the study, we evaluated the effect of training on arterial pressure, the capacity for aerobic work and cardiac function. our results demonstra ... | 1995 | 7584822 |
| the role of the left atrial appendage. a volume loading study in open-chest dogs. | although the left atrial appendage has a quite unique structure, its function remains unclear. to clarify the function of the left atrial appendage, changes in its anteroposterior, transverse and longitudinal dimensions, and in the anteroposterior dimension of the left atrial body were measured by a sonomicrometer during volume loading in open chest dogs. in the control state, fractional shortening of the transverse dimension of the appendage was greater than that of the atrial body. after dextr ... | 1995 | 7596042 |
| a model of human microvascular exchange. | a compartmental model consisting of the circulation, a general interstitium, and the lymphatics, is formulated to describe the transport and distribution of fluid and plasma proteins (albumin) in the human microvascular exchange system. transcapillary mass exchange is assumed to occur via a coupled starling mechanism. unknown or poorly quantified model parameters are estimated by statistical fitting of simulation predictions to five different sets of experimental data. the data consist of steady ... | 1995 | 7603353 |
| peritoneal fluid and tracer albumin kinetics in the rat. effects of increases in intraperitoneal hydrostatic pressure. | to study the peritoneal fluid loss rate, the clearance (ci) of radioactive tracer albumin (risa) eliminated from the peritoneal cavity (pc), as well as the peritoneal-to-plasma risa clearance (ci-->p) during acute peritoneal dialysis (pd) at large elevations in intraperitoneal hydrostatic pressure (ipp). | 1995 | 7612731 |
| effects of heart rate on left atrial contractile performance and left ventricular filling during atrial systole in dogs. | left ventricular (lv) diastolic filling and left atrial (la) contribution have been investigated in patients with heart disease. however, many of these studies were not conducted at a constant heart rate, and the effects of heart rate remain unclear. the purpose of this study was to clarify the effects of the heart rate on left atrial contractile performance and left ventricular filling during atrial systole. the changes in la and lv dimensions and pulmonary venous (pv) flow were determined in 9 ... | 1995 | 7650843 |
| age-related changes in rat interstitial matrix hydration and serum proteins. | measurements of effects of age-related changes on loose connective tissue protein concentrations and water are lacking. tissue hydration is an important determinant of tissue protein diffusion coefficients and hydraulic conductivity. sprague-dawley rats (ages 11, 30, 57, and 89 wk) were anesthetized. blood and mesenteric tissue samples were taken. tissue water content was determined by microgravimetric technique. protein content was determined by electrophoresis. tissue hydration decreased 18% b ... | 1995 | 7671020 |
| the ventricular-synchronous, skeletal-muscle ventricle: preliminary feasibility studies. | the two requirements for the optimal use of skeletal muscle wrapped around a pouch used to pump blood are:(1) a low pouch diastolic pressure (to assure a high muscle capillary blood flow; and (2) a high pouch precontraction pressure (pcp) (to assure a forceful muscle contraction). both requirements are satisfied with the pumping method described herein. this new type of skeletal-muscle ventricle (smv) consists of a rectus abdominis muscle wrapped around a pouch connected to the left ventricular ... | 1993 | 7686661 |
| [cardiodynamics and cardiac pump function in hyperthermia]. | disorders of myocardial pumping function were shown in experimental dogs under hyperthermia. end-systolic, end-diastolic and stroke volume were decreased under those conditions. the effectiveness of frank-starling mechanism was reduced in severe hyperthermia. | 1993 | 7690614 |
| general pattern and morphological specializations of the avian cochlea. | in different bird species, there is a common pattern in the hair-cell morphology and innervation of the basilar papilla; the absolute values, however, are species-specific. in the barn-owl papilla, an extreme being case, the basal high-frequency part of the papilla is greatly expanded. in this behaviorally most important frequency range of the barn owl, the number of afferent nerve terminals to neural hair cells is extensively increased. instead of about 2 afferent terminals as in other species, ... | 1994 | 7701304 |
| regulation of the structural remodelling of the myocardium: from hypertrophy to heart failure. | the framingham heart study has shown that arterial hypertension is the major aetiological factor for the development of heart failure. in the presence of heart failure, various regulatory systems may be operative. these include the frank-starling mechanism, the neurohormonal system, regulation of cardiac growth and peripheral oxygen delivery. recently, the interrelationship of the neuroendocrine system and cardiac growth has been examined. in the pressure or volume overloaded heart, growth of th ... | 1994 | 7713113 |
| the size of the heart. | the size of the heart varies very little over a whole range of normal physiological activities. physiologists, in animals and man, measure changes in cardiac output and heart volumes during exercise. cardiac output can increase 5, 6, or 7 times in athletes but the stroke volume never more than doubles, the end-diastolic volume increases only by about 50% and the end-systolic (residual) volume decreases by the same amount; the heart rate increases about two and a half times in the untrained to 5 ... | 1994 | 7742481 |
| myocardial function in septic sheep. | there is an ongoing discussion whether the heart is the primary target organ responsible for the development of cardiovascular failure during septic shock as well as its onset. we tried to study the reaction of the heart to sepsis in the early phase of 8 h, using a sublethal model of sepsis in six awake cross-bred austrian mountain sheep. sepsis was induced by infusion of a live escherichia coli suspension at a dose of 5 x 10(7) colony-forming units per kg body weight over 8 h. standard hemodyna ... | 1994 | 7743334 |
| pulmonary capillary wedge pressure estimates of left ventricular preload are inaccurate in endotoxin shock: contribution of starling resistor forces to septic pulmonary hypertension. | we tested the hypothesis that starling resistor forces play a significant role in the increase in pulmonary vascular resistance during endotoxin shock. anesthetized pigs (n = 9) were given escherichia coli endotoxin (etx; .5 mg/kg intravenously over 30 min). mean pulmonary arterial pressure (mpap) and pulmonary capillary wedge pressure (pcwp) were recorded through a swan-ganz catheter. pulmonary capillary pressure (pc) was obtained from the analysis of the transient pulmonary artery pressure dec ... | 1994 | 7743360 |
| effects of hypertonic-hyperoncotic infusion on the human atrial natriuretic factor in a standardized clinical trial. | hypertonic-hyperoncotic solutions (hht) are presently being utilized to resuscitate patients in shock. however, so far, the effects of hht on human atrial natriuretic factor (hanf) have not yet been investigated in a clinical trial. the effects of hht on hanf were studied in a standardized preoperative and clinical setting in patients undergoing aneurysmectomy. twenty-three conscious patients were included in two groups: 11 hht and 12 hes (hht: 7.5% nacl/10% hes 200; hes: .9% nacl/10% hes 200). ... | 1995 | 7749942 |
| transcapillary starling forces using membrane osmometry. | membrane osmometry was used to estimate the four transcapillary starling pressures in subcutaneous tissue of rats, guinea pigs, and dogs. isolated subcutaneous tissue samples were either placed on a large-pore or small-pore osmometer that measured the interstitial fluid pressure (pif) and the difference between the interstitial fluid pressure and the interstitial protein osmotic pressure (pif-pi if), respectively. the colloid osmotic pressure of the interstitial fluid (pi if) was obtained from t ... | 1980 | 7386647 |
| [design, manufacturing, and testing of a pulsatile ventricular assist device]. | to describe the design of a ventricular assist device (vad), its manufacturing and testing. | 1994 | 7778999 |
| design, manufacturing, and testing of a paracorporeal pulsatile ventricular assist device: são paulo heart institute vad. | this paper describes the design of a ventricular assist device (vad), its manufacturing, and testing. the vad presented is pulsatile, with a free-floating membrane, smooth internal surfaces, and pericardial valves. it comprehends also a pneumatic driving unit capable of operating in the "full to empty," ekg synchronized or asynchronous modes. in vitro tests were performed to assess its mechanical durability, hydrodynamic performance, and hemolysis. to optimize cannulas and implant techniques, we ... | 1995 | 7779018 |
| osmotic compression of single cardiac myocytes eliminates the reduction in ca2+ sensitivity of tension at short sarcomere length. | according to the frank-starling relation, cardiac output varies as a function of end-diastolic volume of the ventricle. the cellular basis of the relation is thought to involve length-dependent variations in ca2+ sensitivity of tension; ie, as sarcomere length is increased in cardiac muscle, ca2+ sensitivity of tension also increases. one possible explanation for this effect is that the decrease in myocyte diameter as muscle length is increased reduces the lateral spacing between thick and thin ... | 1995 | 7788878 |
| collyricloides massanae vaucher, 1969, in a starling (sturnus vulgaris l.) in the netherlands. | collyricloides massanae (trematoda: collyriclidae) is described from cysts in the wall of the small intestine of a starling (sturnus vulgaris l.) in the netherlands. the original descriptin was from a yellow necked mouse, apodemus flavicollis (melchior), so this is the first record of the species in birds. | 1980 | 7410811 |
| neural, hormonal and intrinsic mechanisms of cardiac control during acute coronary occlusion in the intact dog. | three basic mechanisms may be involved in the control of cardiac function during acute coronary occlusion: (1) neural; (2) hormonal (circulating catecholamine); and (3) intrinsic (e.g. frank--starling law). the response of intact, sedated (innovar-vet, 0.08 cc/kg), chronically instrumented dogs to a 5 min left circumflex coronary occlusion was tested to delineate the relative roles of each of the above mechanisms. first, 6 innervated and 6 cardiac denervated dogs were examined. the major differe ... | 1981 | 7264197 |
| the cardiac structure-function relationship and the renin-angiotensin-aldosterone system in hypertension and heart failure. | according to the framingham study, arterial hypertension and coronary artery disease are the major etiologic factors in the development of heart failure. regulatory systems that may affect heart failure include the frank-starling mechanism, neurohormonal responses, cardiac growth and peripheral oxygen delivery. recently, the interrelationship between the neuroendocrine system and cardiac growth has aroused much interest. in the pressure- or volume-overloaded heart, hypertrophic growth of the myo ... | 1994 | 7827369 |
| the role of platelet-activating factor in lipopolysaccharide-induced myocardial depression in guinea pigs. | to determine if platelet-activating factor (paf) is a key mediator of lipopolysaccharide (lps)-induced myocardial depression in guinea pigs. | 1995 | 7757142 |
| starling resistor vs. distensible vessel models for embolic pulmonary hypertension. | we investigated whether the starling resistor model (mitzner et al. j. appl. physiol. 51: 1065-1071, 1981) or a distensible vessel model (haworth et al. j. appl. physiol. 70: 15-26, 1991) best describes pulmonary vascular pressure-flow (q) relationships in embolic pulmonary hypertension. mean pulmonary arterial pressure (ppa)-q plots at constant left atrial pressure (pla) and ppa-pla plots at constant q were investigated in seven dogs before and after 500-micron glass bead pulmonary embolism. em ... | 1995 | 7864209 |
| increased vascular resistance with hemoglobin-based oxygen carriers. | to compare the effects of resuscitation with hemoglobin-based oxygen-carriers and conventional resuscitation fluids on hemodynamics, oxygen transport, and oxygen consumption in an animal model of the use of these fluids in the treatment of hemorrhagic shock. | 1994 | 7994360 |
| chronic alterations in cardiac mechanics after fetal closed heart operation. | pulmonary artery banding was performed in 8 fetal sheep at 125 days' gestation to evaluate the feasibility of fetal closed cardiac operation. at 135 days' gestation, the fetuses were delivered and the cardiac mechanics were evaluated using a modified langendorff isolated heart preparation. two of the 8 fetuses aborted spontaneously 2 and 7 days after operation. six fetuses (75%) survived the 10 days after delivery. the left ventricular cardiac mechanics in the banded fetuses (group i) were compa ... | 1994 | 8010781 |
| an analysis of the interaction between interstitial plasma protein, interstitial flow, and fenestral filtration and its application to synovium. | an analysis of the interstitial flow of a protein solution is presented, based on physical interactions with extracellular matrix biopolymers. previous models were extended by incorporation of three features--(a) interstitial osmotic reflection coefficients and attendant partial molecular sieving, (b) the effect of solute exclusion on apparent intramatrix fluid viscosity, and (c) the effect of discrete capillary porosity on near-pore oncotic and hydraulic gradients. the principles were applied t ... | 1994 | 8022316 |
| experimental transmission of crimean-congo hemorrhagic fever virus by west african wild ground-feeding birds to hyalomma marginatum rufipes ticks. | hyalomma (h.) marginatum rufipes ticks commonly infest birds and are potential vectors of crimean-congo hemorrhagic fever (cchf) virus in west africa. an experimental model for investigating the role of birds in the cchf virus transmission cycle was developed. following cchf virus inoculation, antibodies were detected by enzyme-linked immunosorbent assay in one red-beaked hornbill and one glossy starling, but not in two laughing doves and six domestic chickens. none of the birds showed a detecta ... | 1994 | 8024058 |
| length-dependent modulation of ang ii inotropism in rat myocardium: effects of myocardial infarction. | to determine whether changes in sarcomere length affect the inotropic response of the heart to angiotensin ii (ang ii) differently in dilated and failing myocardium, papillary muscles were removed 2 days after infarction, and the effects of ang ii were studied at various muscle lengths. myocardial infarction, which averaged 52% of the left ventricle inclusive of the interventricular septum, was characterized hemodynamically by left ventricular failure and right ventricular dysfunction. ang ii ad ... | 1994 | 8141379 |
| a radioimmunoassay for recombinant-derived chicken prolactin suitable for the measurement of prolactin in other avian species. | a homologous radioimmunoassay for chicken prolactin is described. the assay is based on recombinant-derived chicken prolactin that has been used to raise an antibody and produce 125i-labeled tracer and assay standards. the radioimmunoassay measures a minimum of 0.03 +/- 0.01 ng of the recombinant prolactin with 50% displacement of binding by 0.6 +/- 0.1 ng. chicken plasma and pituitary immunoreactivity dilute in parallel with the standard curve. the mean (+/- se) concentrations of plasma prolact ... | 1994 | 7883142 |
| starling pressures in the human arm and their alteration in postmastectomy oedema. | 1. surgery and radiotherapy to axillary lymph nodes during breast cancer treatment is often followed, commonly years later, by chronic postmastectomy oedema (pmo). pmo is considered a 'high protein' oedema due to reduced axillary lymph drainage. since oedema formation also depends on fluid input (capillary filtration), we studied the starling pressures in the affected and contralateral arm. colloid osmotic pressure was measured in patient serum (pi p) and interstitial fluid (pi i). subcutis flui ... | 1994 | 7932226 |
| cyclophosphamide effects on immune function of european starlings. | we developed and tested a battery of immune function assays on adult european starlings (sturnus vulgaris) exposed to the immunotoxicant cyclophosphamide (cy). starlings were injected intraperitoneally for three consecutive days with saline or 20 mg/kg cy. cyclophosphamide did not affect body mass or packed cell volume. however, spleen to body mass ratios and the number of viable spleen cells were lower in cy-treated birds when compared to controls. peripheral white blood cell numbers were reduc ... | 1994 | 7933273 |
| [physiologic pacemaker therapy for drug-resistant heart failure in a patient with dilated cardiomyopathy and first-degree atrioventricular block: a case report]. | this is a report of a 65-year-old man with end-stage dilated cardiomyopathy, and first-degree atrioventricular (av) block, which had been resistant to intensive medical therapy and was eventually treated using a ddd pacemaker. the optimal av interval setting was determined using invasive right heart catheterization and doppler echocardiography. at a pacing rate of 92/min, an av interval setting between 200 and 100 msec increased left ventricular filling and enhanced myocardial contractility. an ... | 1993 | 8164130 |
| modeling the transient response to volume perturbations in the beating heart by the difference equation method. | discrete theoretical methods, compatible with the discrete features of the beating heart, are used together with experimental study to attain a quantitative understanding of the transient response to a volume perturbation and of sustained mechanical alternans (sma) in the beating heart. this is done in three stages. in stage a, a first-order difference equation describes the stroke volume (sv) response due to the frank-starling mechanism. it is shown that the value of gamma, the slope of the sv- ... | 1994 | 8184945 |
| three-dimensional transmural mechanical interaction between the coronary vasculature and passive myocardium in the dog. | the "garden hose" effect of coronary perfusion on diastolic left ventricular (lv) mechanics has been proposed to cause changes in systolic function by altering diastolic sarcomere length. we measured transmural distributions of three-dimensional shape change using radiopaque markers implanted in the lv free wall of eight isolated arrested canine hearts as functions of coronary arterial perfusion pressure (pp) and lv pressure (plv) and related these deformations to the local muscle fiber architec ... | 1994 | 8187283 |
| the relationship of intracranial venous pressure to hydrocephalus. | little is known about intracranial venous pressure in hydrocephalus. recently, we reported that naturally occurring hydrocephalus in beagle dogs was associated with an elevation in cortical venous pressure. we proposed that the normal pathway for cerebrospinal fluid (csf) absorption includes transcapillary or transvenular absorption of csf from the interstitial space and that the increase in cortical venous pressure is an initial event resulting in decreased absorption and subsequent hydrocephal ... | 1994 | 8194060 |
| left-to-right ventricular interaction with a noncontracting right ventricle. | left ventricular systole is known to contribute to generation of right ventricular pressure and stroke volume. to study the interactions in a dilated noncontractile right ventricle after cardiopulmonary bypass we created a variable volume, neo-right ventricle by excision and replacement of the right ventricular free wall with a xenograft pericardial patch. we investigated the interactions in eight dogs with neo-right ventricle, instrumented to measure cardiac pressures and cardiac output in cont ... | 1994 | 8196395 |
| extravascular protein in the renal medulla: analysis by two methods. | two methods have been used to test for the presence of extravascular protein in the interstitium of the renal inner medulla. first, ascending vasa recta (avr) segments were perfused with buffer containing 5 g/dl of albumin. the hydraulic pressure in the perfused vessel was varied to control transmembrane volume flux (jv) to the interstitium. interpolation to the point of zero jv was employed to estimate interstitial starling forces in the hydropenic rat papilla. analysis of those experiments pre ... | 1994 | 8203616 |
| effect of extravascular plasma protein on pressure-flow relations across synovium in anaesthetized rabbits. | 1. the effect of extravascular plasma protein on fluid flux through interstitial matrix was investigated in vivo by studying the pressure-flow relation across synovium during intra-articular infusions of protein solutions (usually bovine serum albumin). synovium is a sheet of non-epithelial cells separated by interstitium-filled gaps, beneath which are fenestrated capillaries: synovium regulates synovial fluid volume and composition. 2. albumin solutions (10-150 g l-1) of measured oncotic pressu ... | 1993 | 8229849 |
| exhaustion of frank-starling mechanism in conscious dogs with heart failure. | the goal of this study was to elucidate the ability of the left ventricle to accommodate an increase in preload (frank-starling mechanism) in the presence of congestive heart failure (chf) but in the absence of the complicating effects of hypertrophy and fibrosis. to accomplish this, the effects of volume loading were examined in eight conscious dogs during the control state and after 3 wk of right ventricular pacing (240 beats/min). chf increased heart rate (by 16 +/- 5 from 92 +/- 5 beats/min) ... | 1993 | 8238398 |
| [ventricular function in animals undergoing renal mass ablation. effect of blood pressure control]. | the causes of left ventricular hypertrophy (lvh) in chronic renal failure are multifactorial. the tail arterial pressure, heart weight, maximum developed pressure and pressure-volume relationship in animals with 5/6 nephrectomy (crf, n = 16) and crf animals who received furosemide by oral gavage (crf-f, n = 17) were studied. all crf animals increased their blood pressure (basal: 117.2 +/- 0.8; 6th week: 184.8 +/- 2.9, p < 0.001) but in those treated with furosemide the blood pressure stayed with ... | 1993 | 8242106 |
| continuing development of the cleveland clinic-nimbus total artificial heart. | a completely implanted total artificial heart (tah) is under development by nimbus, inc., and the cleveland clinic foundation (ccf). key features of the system include an electrohydraulic energy converter, an automatic control system that produces a frank-starling response, and dual ventricles composed of graphite-epoxy and titanium with gelatin blood contacting surfaces. the system is controlled by a single substrate, hybridized microcircuit (the hybrid). fabrication of the tah control hybrid h ... | 1993 | 8268522 |
| an atrial hydraulic shunt in a total artificial heart. a balance mechanism for the bronchial shunt. | an implantable tah must be able to maintain physiologic atrial pressures over a range of left side shunt flows, which in humans can range up to 5% of the total cardiac output (co). the authors describe the characteristics of an atrial hydraulic shunt in an electrohydraulic tah. a small (10 cc stroke) chamber placed in line between the left atrial cuff and the inflow valve is shunted to the right hydraulic chamber. high left atrial pressure increases the volume displaced by this chamber; this con ... | 1993 | 8268531 |
| [cardiodynamics and cardiac pump function in hyperthermia]. | breaking of myocardial pumping function was shown in experiments in anesthesized dogs under hyperthermia. the end-systolic, end-diastolic and stroke volume was decreased under those conditions. the effectiveness of frank-starling mechanism was reduced in severe hyperthermia. | 1993 | 8274672 |
| a model of human microvascular exchange: parameter estimation based on normals and nephrotics. | a mathematical model is formulated and used to describe the distribution and transport of fluid and albumin in the human circulation, interstitium and lymphatics. two transcapillary mass exchange mechanisms are investigated: a homoporous 'coupled starling model', in which transcapillary albumin diffusion and convection occur within the same pathway, and a heteroporous 'plasma leak model', in which variations in structure and pressure are permitted along the length of the capillary. parameters us ... | 1993 | 8275681 |
| response of arterial resistance and critical pressure to changes in perfusion pressure in canine hindlimb. | the dynamic pressure-flow relationship in the canine hindlimb at normal arterial pressure is best explained by modeling a starling resistor (critical pressure, pcrit) at the level of the arterioles. regulation of flow can therefore occur at the starling resistor through changes in pcrit or along the length of the vessel through changes in arterial resistance (ra). we hypothesized that increasing perfusion pressure (pper) would increase pcrit due to the myogenic response but would decrease ra bec ... | 1993 | 8285232 |
| plasmalemmal vesicles represent the large pore system of continuous microvascular endothelium. | in the capillary physiology literature, molecules and particles larger than 10 nm are assumed to leave the plasma mostly through large pores located at the level of intercellular junctions in microvessels lined with a continuous endothelium. in morphological studies of similar microvessels, outgoing particles > 10 nm were detected in endothelial plasmalemmal vesicles not in intercellular junctions. because the probes may not be found in transit through the junctions because they may be swept awa ... | 1993 | 8368373 |
| auditory frequency generalization and a failure to find octave generalization in a songbird, the european starling (sturnus vulgaris). | many species of songbirds have absolute pitch perception. they memorize tones when discriminating between sequences and fail to generalize to novel frequency ranges. i examined frequency generalization in starlings (sturnus vulgaris) that were trained to discriminate between individual frequencies. starlings were tested for frequency generalization after training on 2- and 3-tone discriminations. there was no evidence for octave generalization, which is a hallmark of human absolute pitch percept ... | 1993 | 8370267 |
| a near perfect temperature adaptation of bilayer order in vertebrate brain membranes. | the bilayer order of a brain synaptic membrane fraction from a number of fish, mammalian and avian species have been compared in relation to their respective body temperatures using steady-state and time-resolved fluorescence anisotropy techniques. fluorescence anisotropy for both 1,6-diphenyl-1,3,5-hexatriene and trans-parinaric acid increased in the order: antarctic notothenia, trout, perch, cichlid, rat and starling, this also being the order of increasing body temperature. this suggests that ... | 1993 | 8373797 |
| anion manipulation, a novel antiarrhythmic approach: mechanism of action. | we recently reported that modulation of anion homeostasis by substitution of extracellular chloride by nitrate prevents ischaemia- and reperfusion-induced ventricular fibrillation (vf) in rat and rabbit in vitro by an unknown mechanism independent of haemodynamic changes but related to widening of qt interval (ridley and curtis 1991). in the present study we have examined three possible explanations for the mechanism: modification of membrane anion permeability, alteration of cyclic nucleotide h ... | 1993 | 8393492 |
| regional geometry and function during myocardial ischemia and recovery. | to define the effects of altered left ventricular (lv) geometry on regional myocardial function during ischemia and recovery, regional and global lv geometry and transmural pressure (p) were measured in seven conscious dogs with sonomicrometry and micromanometry. data were obtained at steady state and during rapid vena caval occlusion (vco) under control conditions, after 15 min of left anterior descending occlusion, and after 1, 4, and 24 hr of reperfusion. regional midwall minor axis (ma) lagr ... | 1993 | 8412064 |
| pressure-volume relationship of the fetal lamb heart. | in contrast to the adult heart, the fetal heart reportedly has little functional reserve. with increased clinical emphasis on fetal cardiac diagnosis, neonatal surgery, and the potential for future fetal cardiac intervention, it is essential that we better understand fetal cardiac function. therefore, to demonstrate the extent of fetal cardiac preload reserve, we studied 10 fetal lambs using an isolated, isovolumic, blood-perfused heart preparation. we maintained constant afterload, inotropic st ... | 1993 | 8431061 |
| effect of changes in aortic pressure and in coronary arterial pressure on left ventricular geometry and function anrep vs. gardenhose effect. | sudden increases in aortic pressure (aop, mm hg) are associated with increases in left ventricular (lv) function which persist even after diastolic volume has returned to its initial value (anrep effect). likewise, increases in coronary arterial pressure (cap, mm hg) are associated with improved lv function (gardenhouse effect). in situ, increases in aop are paralleled by increases in both cap and coronary blood flow, i.e., oxygen supply. we investigated the individual contributions of aop and c ... | 1993 | 8147826 |
| 5'-nucleotidase inhibition enhances postischemic myocardial performance. | adenosine methylene diphosphate (ampcp), a 5'-nucleotidase inhibitor, was evaluated as an adjunct to cold crystalloid cardioplegic myocardial protection. cardiopulmonary bypass (cpb) was instituted at 28 degrees c in two groups of mongrel dogs (each, n = 6). myocardial ischemia was induced for 150 min by aortic cross clamping. crystalloid cardioplegia (4 degrees c) was infused into the aortic root at 15 ml/kg/20 min in the control group (cp). the experimental group (cp + ampcp) received identica ... | 1994 | 8152230 |
| the failing human heart is unable to use the frank-starling mechanism. | there is evidence that the failing human left ventricle in vivo subjected to additional preload is unable to use the frank-starling mechanism. the present study compared the force-tension relation in human nonfailing and terminally failing (heart transplants required because of dilated cardiomyopathy) myocardium. isometric force of contraction of electrically driven left ventricular papillary muscle strips was studied under various preload conditions (2 to 20 mn). to investigate the influence of ... | 1994 | 8156643 |
| geometric and muscle physiological factors of the frank-starling mechanisms. | the relation between left-ventricular stroke volume (sv) and end-diastolic volume (edv) was determined based on angiocardiographic measurements in 10 open-chest minipigs under varying filling conditions (blood letting or infusions). the results were compared with a theoretical relation calculated under the assumption of varying edv but constancy of myocardial properties. in contrast to the linear increase of sv as a function of edv as found in the animal experiments, the calculated curve reveals ... | 1993 | 8471007 |
| analysis of endotoxin effects on pulmonary circulation in terms of pressure-flow characteristics. | the purpose of the present work was to explore the hypothesis that pulmonary vasoconstriction secondary to endotoxin insult results mainly from an increase in the critical closing pressure of the pulmonary vessels. specifically, we reasoned that in the face of a starling resistor located between pulmonary arteries and left atrium, upstream transmission of increased left atrial pressure (pla) would be inversely related to the level of the pressure intercept (pi) obtained by extrapolation from the ... | 1993 | 8485820 |
| capillary filtration coefficients using laser densitometry and gravimetry in isolated dog lungs. | we compared pulmonary capillary filtration coefficients (kf,c) using measurements of transcapillary filtration rates based on laser densitometry of perfusate hematocrit changes (jy,l) and gravimetric measurement of the rate of lobe weight gain (delta wt/delta t) after an increase in capillary pressure (pc) in isolated autologous blood-perfused dog lungs. although the lobe weight increased at a rate that decreased with time, the densitometric filtration rate was relatively constant over time. kf, ... | 1993 | 8514719 |
| mechanisms of the frank-starling phenomena studied in intact hearts. | the impact of ventricular volume on the relationship between intracellular calcium and ventricular pressure under steady-state conditions was determined in intact ferret hearts. the results reveal major quantitative differences and minor qualitative differences between these relations and those previously measured in isolated intact and skinned cardiac muscle. the importance of these differences is discussed within the context of developing a comprehensive mechanistic theory to describe load-dep ... | 1995 | 8540392 |
| distortion-product otoacoustic emissions and their anaesthesia sensitivity in the european starling and the chicken. | the aim of the present experimental series was to provide further information on the distortion-product otoacoustic emissions (dp) of birds and contribute to a general understanding of dp generation. basic characteristics of the dp 2f1-f2 and 2f2-f1 were measured in the ear canal of both awake and anaesthetized european starlings and chickens. the effect of a third suppressive tone and the behaviour of the dp under anaesthesia were also studied. in general, the dp characteristics of both bird sp ... | 1995 | 8567421 |
| haemodynamic basis for the development of left ventricular failure in systolic hypertension and for its logical therapy. | in youth, properties of the human arterial system are such that pulse pressure generated by ventricular ejection is low, and the major component of wave reflection returns to the heart after the aortic valve has shut, so making no contribution to ventricular load, but boosting pressure throughout diastole and so aiding coronary perfusion. that constitutes optimal arterial function and optimal vascular/ventricular interaction. with ageing, the aorta and elastic arteries stiffen, so that aortic pu ... | 1995 | 8586828 |
| nonlinear resistances in hepatic microcirculation. | the liver provides a reservoir available for mobilizing large amounts of blood, but if a change in downstream (outflow) pressure below a certain magnitude (break pressure) does not change upstream pressures, blood volume redistribution may be limited. for downstream pressures larger than the break pressure, the upstream pressures change proportionately. we tested the hypothesis that this nonlinear mode of pressure transmission could be found from the abdominal vena cava to the hepatic microcircu ... | 1995 | 8594900 |
| the effect of lazaroid (u74500a), a novel inhibitor of lipid peroxidation, on 24-hour heart preservation. a study based on a working model using cross-circulated blood-perfused rabbit hearts. | lazaroid, an inhibitor of iron-mediated lipid peroxidation, has been shown to reduce free radical-mediated injury after ischemia and reperfusion. we thus examined the efficacy of pretreatment with lazaroid (u74500a) in enhancing functional recovery after 24-hr heart preservation. an isolated rabbit heart model perfused with the blood from a support rabbit was used. before preservation, either u74500a (4 mg/kg, group l; n = 6) or solvent (group s; n = 7) was given to the donor rabbit. after 24-hr ... | 1996 | 8600622 |
| pulmonary vasoconstriction due to impaired nitric oxide production after cardiopulmonary bypass. | pulmonary hypertension is a serious complication after cardiopulmonary bypass (cpb). this study tests the hypothesis that cpb provokes oxidant-mediated pulmonary endothelial dysfunction, leading to reduced nitric oxide (no) production and pulmonary vasoconstriction. | 1996 | 8651783 |
| left ventricular mechanoenergetics under altered coronary perfusion in guinea pig hearts. | coronary perfusion pressure (cpp) is well known to affect left ventricular (lv) mechanoenergetics (gregg's phenomenon). the garden hose effect via the frank-starling mechanism caused by coronary distension has long been considered to be the underlying mechanism of this phenomenon. however, recent studies have revealed a close correlation between cpp and the excitation-contraction coupling in myocytes. the aim of this study was to investigate the mechanoenergetic aspects of gregg's phenomenon by ... | 1995 | 8676582 |
| plasma thyroid hormone and growth hormone patterns in precocial japanese quail and altricial european starlings during postnatal development. | plasma concentrations of thyroid hormones (th) and growth hormone (gh) during postnatal development in the precocial japanese quail (coturnix japonica), and the altricial european starling (sturnus vulgaris) were measured. developmental changes in plasma th found in the starling, differ considerably from those detected in quail. in quail rather high triiodothyronine (t3) values were measured during the first few days after hatching. subsequently a steady decrease of plasma t3, to adult levels, w ... | 1996 | 8689527 |
| comparison of the ontogenesis of thyroid hormones, growth hormone, and insulin-like growth factor-i in ad libitum and food-restricted (altricial) european starlings and (precocial) japanese quail. | in this study, we compare the ontogenic patterns for thyroid hormones, growth hormone (gh), and insulin-like growth factor-i (igf-i) in altricial european starlings and precocial japanese quail and examine the effects of feed restriction on these species. the most marked difference in development between the altricial and precocial birds was with respect to plasma thyroid hormone patterns. in the starling, circulating concentrations of triiodothyronine (t3) and thyroxine (t4) were very low in em ... | 1996 | 8729940 |
| assessment of the frank-starling relationship by two-dimensional echocardiography. | the frank-starling relationship between left ventricular stroke work and end-diastolic minor-axis cross-sectional area was evaluated as a load-insensitive measure of inotropic state by two-dimensional echocardiography in 10 conscious dogs. stroke work was calculated as the product of systolic change in cross-sectional area and either (1) beat-to-beat mean arterial pressure or (2) initial systolic blood pressure. both frank-starling relationships were highly linear during preload variation (mean ... | 1996 | 8736005 |
| microvascular architecture and exchange in synovial joints. | the microcirculation of the synovial lining of joints displays many fascinating adaptations to function. one primary function is to supply nutrients to the avascular cartilage, whose chondrocytes are metabolically active but are relatively vast distances from the nearest capillary (> 1 cm in the center of a human knee). exchange is facilitated by a high density of fenestrated capillaries situated very close to the synovial surface (an arrangement disrupted in rheumatoid synovium) with fenestrati ... | 1995 | 8748946 |
| paracrine modulation of heart cell function by endothelial cells. | an accumulating body of experimental data supports the presence of a paracrine pathway for the modulation of myocardial function by cardiac endothelial cells. cardioactive substances released by endothelial cells include nitric oxide, endothelin-1, prostanoids, adenylpurines, natriuretic peptides, and other agents that have so far only been characterised in bioassay studies. endothelial cells also possess enzymatic activities, in particular ace/kininase activity, which can alter local levels of ... | 1996 | 8759239 |
| functional effects of emd-57033 in isovolumically beating isolated rabbit hearts. | the results of isolated myocyte and cardiac muscle experiments indicate that inotropic agents that increase responsiveness of myofilaments to ca2+ (so-called ca2+ sensitizers) may prolong myocardial contraction and increase diastolic tone, but the importance of these effects in the whole heart is unclear. therefore, we studied the effects of the ca2+ sensitizer emd-57033 (emd) on left ventricular (lv) contractile events and passive properties in isovolumically beating isolated rabbit hearts that ... | 1996 | 8760157 |
| the in vivo quantification of myocardial performance in rabbits: a model for evaluation of cardiac gene therapy. | evaluating cardiac gene therapy in the intact animal requires an index of cardiac function capable of detecting regional differences in contractility in a load-independent fashion. potentially load-insensitive measures of ventricular performance were therefore evaluated in 10 open- and closed-chested, anesthetized rabbits. lv transmural pressure and myocardial segment length were measured using micromanometry and sonomicrometry during steady-state and transient inferior vena caval occlusion, ove ... | 1996 | 8762021 |
| length-dependent activation in intact ferret hearts: study of steady-state ca(2+)-stress-strain interrelations. | we examined the steady-state stress-strain relationships and the steady-state stress-intracellular calcium concentration ([ca2+]i) relationship in intact ferret hearts and compared these to previously published analogous relationships in skinned and intact muscle. langendorff-perfused ferret hearts were treated with ryanodine and tetanized by rapid stimulation to create steady-state conditions. [ca2+]i was measured concurrently by macroinjected aequorin. over a range of volumes corresponding to ... | 1996 | 8764242 |