Search Results
Results 551 - 600 of 1526
< 7 8 9 10 11 12 13 14 15 16 17 >
Mc Parland B E - - 1998
In vivo agonist delivery to the lungs is characterized by absorption through the mucosal layer followed by access to the smooth muscle. When agonists are applied to perfused bronchial segments, a difference in potency to agonists applied to the serosal (outside) or mucosal (inside) surface can be demonstrated. In order ...
Ay I - - 1998
1. In isolated perfused rat kidney, under a constant flow of 8-10 ml/min, mean basal perfusion pressure was found to be 82.57 +/- 8.96 mm Hg (n = 70). 2. After a bolus injection of 10 micrograms/0.1 ml phenylephrine (PE) which causes maximum vasopressor response, a 93.27 +/- 0.56 mm ...
Samsom M - - 1998
The development of solid-state catheters with miniature pressure transducers and portable dataloggers with a large memory capacity has allowed recording of gastrointestinal motility in ambulant subjects. Developments in silicone rubber extrusion technology made it possible to build a perfused manometric system, using a perfused manometric assembly requiring a low volume ...
Pintér A - - 1998
Vasoactive intestinal polypeptide (VIP) was either injected intravenously (300 pmol.kg-1) or perfused (1 nmol in 1 min) into the sinus node artery (SNA) in anesthetized dogs to study its effect on subsidiary atrial pacemakers. Isochronal maps were obtained from 128 unipolar electrograms recorded on the epicardial surface of both atria ...
Kleen M - - 1998
Hypervolaemic haemodilution makes myocardial perfusion more homogenous as reflected by reduced fractal dimension of regional myocardial perfusion. The clinically more commonly performed acute normovolaemic haemodilution, however, has not yet been studied in this respect. Hyperoxic ventilation with 100% oxygen is used in conjunction with haemodilution to compensate for low oxygen ...
Eze A R - - 1998
Intermittent lower extremity compression increases cutaneous blood flow. The source of this increased perfusion and, the influence of physical activity on stimulated foot skin perfusion has not been elucidated. The purpose of this study is to determine the arterial and venous contributions to augmented cutaneous blood flow during foot and ...
Lecour S - - 1998
The present study was designed to identify the free radicals generated during the electrolysis of the solution used to perfuse isolated rat heart Langendorff preparations. The high reactivity and very short half-life of oxygen free radicals make their detection and identification difficult. A diamagnetic organic molecule (spin trap) can be ...
Nagasawa S - - 1998
A simulation study was undertaken using a compartmental flow model of a large high-flow cerebral arteriovenous malformation to investigate the hemodynamic changes during obliteration procedures. Under certain autoregulatory conditions, marked hyperperfusion (92 ml/100 g/min) could be induced in association with increased wall stress of the arterioles. Narrowing of the autoregulatory ...
Achtert A D - - 1998
BACKGROUND: The purpose of this investigation was to determine the accuracy of the estimation of ejection fractions (EFs) and left ventricular volumes from a commercially available software package (Quantitative Gated SPECT [QGS]) as a function of different true EFs, count level in the acquisitions, severity and location of perfusion defects, ...
Thorén A - - 1998
Reduction of central blood volume elicits a peripheral vasoconstrictor reflex in various tissues including skin, skeletal muscle and the hepatomesenteric region. The aim of the present study was to investigate whether this reaction includes a decreased perfusion of the jejunal mucosa in man. Laser Doppler flowmetry (LDF) was used to ...
Kincaid E H - - 1998
Inadequate splanchnic perfusion, detected as a low gastric intramucosal pH (pHi), in the face of normal systemic perfusion predicts an increased risk for multiple organ failure after trauma. Although the exact etiology of this low pHi is unknown, angiotensin II is thought to be an important regulator of gut perfusion ...
Dean D A - - 1998
BACKGROUND: The relative merits of antegrade infusion and retrograde infusion of cardioplegic solution in terms of heart weight, myocardial water content, and ventricular diastolic properties are undefined. Accordingly, we compared antegrade and retrograde flow of hemodiluted blood in isolated, hypothermic porcine hearts. METHODS: After cardiectomy, 1 L of cold heparinized ...
Segel L D - - 1998
BACKGROUND: These experiments were designed to evaluate the viability of large hearts after preservation by use of procedures that have shown good results with small animal hearts. Efficacy of novel long-term preservation protocols should be documented with a large animal model before such procedures can be adopted for clinical use. ...
Dijkman M A - - 1998
The perfusion-induced increase in cardiac contractility (Gregg phenomenon) is especially found in heart preparations that lack adequate coronary autoregulation and thus protection of changes in capillary pressure. We determined in the isolated perfused papillary muscle of the rat whether cardiac muscle contractility is related to capillary perfusion. Oxygen availability of ...
Tufto I - - 1998
Studies of interrelationships between physiological parameters of tumours are sparse. The possibility that vascular density might be related to the rate of angiogenesis, the rate of perfusion and/or the development of necrosis was examined in the work reported here. Xenografted tumours of four human melanoma cell lines (A-07, D-12, R-18 ...
Hagihara A - - 1998
The present study was designed to combine the monophasic action potential (MAP) recording technique with a well-established canine isolated, blood-perfused ventricular septum preparation for examining, simultaneously, electrical and mechanical drug-induced changes. A MAP catheter was positioned onto the base of a papillary muscle for recording the local MAP, using a ...
Rankin J C - - 1998
We review the literature on the way the structure of icefish gills relates the physiology of these haemoglobin-less fishes. Vascular casting confirmed earlier reports that the only special feature of the gills is the large size of the blood vessels, especially the prominent and continuous marginal channels Isolated perfused gill ...
DeGrado T R - - 1998
The effects of specific activity of meta-[(131)I]iodobenzylguanidine (MIBG) were studied in uptake-2 blocked isolated perfused rat heart. [(131)I]MIBG was administered in the perfusate as an 8-min pulse, followed by an 80-min washout period. Kinetic analysis of the externally monitored time-activity curves gave estimates of uptake rate and multiexponential clearance. Uptake ...
Kornowski R - - 1998
BACKGROUND: The efficacy of thrombolytic therapy might be influenced by changes in the hemodynamic status. The aim of the study was to examine whether changes in perfusion pressure could affect the time to reflow in an in-vitro model. METHODS: The in-vitro flow system comprised flexible plastic tubes that enclosed a ...
Wangemann P - - 1998
We developed a new technique, the isolated in vitro perfused spiral modiolar artery, which allowed the continuous measurement of the vascular diameter and control of the intravascular pressure. An isolated section of the spiral modiolar artery from the gerbil was perfused on one end with a set of concentric pipettes ...
Peter F W - - 1998
Impaired capillary perfusion may result in flap failure. Platelet emboli, polymorphonuclear leukocytes (PMNs), and/or vasospasm have been identified as possible causes. This study investigates the role of PMNs in causing impaired capillary perfusion in a free flap model. PMN concentrations were depleted using antineutrophil serum. The cremaster muscles of 20 ...
Wainwright C L - - 1997
Previous studies in pigs have shown that the A1-adenosine receptor agonist, R-PIA, is a potent antifibrillatory agent during myocardial ischaemia and that this effect can be overriden by atrial pacing. However, reports of A1-adenosine receptor down-regulation following chronic exposure to A1-receptor agonists suggest that this may limit their use as ...
Byrne B M - - 1997
The role of nitric oxide in hypoxic fetoplacental vasoconstriction (HFPV) was investigated using dually perfused human placental cotyledons. Standard medium (Earle's salt solution with added dextran and L-arginine) was equilibrated with 95 per cent O2 and 5 per cent CO2 (maternal side) and 94 per cent N2 and 6 per ...
Janse M J - - 1997
The authors have conducted several experimental studies of the cellular electrophysiology of the atrioventricular (AV) node employing the Langendorff-blood perfused heart of both dogs and pigs. Two types of experiments are described: experiments showing that cells with electrophysiological characteristics of typical nodal cells can be found outside Koch's triangle; and ...
Martinussen H J - - 1997
In this study, the dynamic interrelationships between myocardial functional state and changes in the second messenger content in pressure-overloaded hypertrophied hearts were investigated. Forty-three rat hearts were used after partial clamping of the abdominal aorta. The isolated hearts were perfused with Krebs-Henseleit buffer and allocated to perfusion for 20 s ...
Park J L - - 1997
The cytoprotective action of reviparin-sodium (LU-47311: Clivarin), a low-molecular-weight heparin, was examined in an ex vivo model of complement-mediated myocardial injury. The effective concentration of reviparin was determined by using an in vitro rabbit erythrocyte-lysis assay using 4% normal human plasma. Reviparin (0.01-2.73 mg/ml) reduced erythrocyte lysis in a concentration-dependent ...
Hoeldtke N J - - 1997
OBJECTIVES: Our purpose was to determine the effects of acidosis and acidosis-hypoxia on fetoplacental perfusion pressure and its response to angiotensin II. STUDY DESIGN: Perfused cotyledons from 14 placentas were studied with either an acidotic fetal circuit perfusate (n = 7) or an acidotic-hypoxic fetal circuit perfusate (n = 7). ...
Watanabe T - - 1997
The single pass type (SP) of blood cardioplegia is commonly used in North America during open heart surgery. However the recirculation type (RC) of blood cardioplegia is still widely used in other areas including Japan. Infusion blood cardioplegia using the latter technique often decreases the perfusion pressure. To determine the ...
Shenkman Z - - 1997
BACKGROUND: Retrograde cerebral perfusion through the superior vena cava (SVC) has been proposed to protect the brain from ischaemic injury during profound hypothermic circulatory arrest (PHCA). Its contribution to cerebral protection is unclear. Furthermore, the addition of anaesthetic or vasodilating agents to the SVC perfusate to enhance brain protection, has ...
Ingemansson R - - 1997
BACKGROUND: The aim of this study was to investigate how much perfusion pressure an artery can tolerate without significant loss of endothelium-dependent relaxation (EDR) and vascular contractility. METHODS: The abdominal aortas of 396 Sprague-Dawley rats were used. One hundred twenty aortas were flush-perfused for 1 or 5 minutes with cold ...
Seely S - - 1997
When the heart contracts, it compresses its own arteries, so that it cannot supply itself with blood during systole. Its perfusion is effected during diastole by an auxiliary pump, which is an elastic reservoir consisting of the aorta and its large branch arteries. During systole this container is distended, storing ...
Rasiah R L - - 1997
We describe a method for multiple indicator dilution studies in the isolated perfused human placental lobule developed to investigate the relationships between changes in pressure and flow and solute clearance. A peripheral lobule of a human placenta is perfused with a tissue culture-based medium and the perfusate oxygen tension, arterial ...
Moravec C S - - 1997
We tested the hypothesis that in the intact heart, mitochondrial metabolism is activated by mitochondrial Ca2+ uptake during increased work. We measured left ventricular pressure (LVP), pyruvate dehydrogenase (PDH) activity, and mitochondrial and A band elemental content by electron probe microanalysis (EPMA) in Langendorff-perfused hamster hearts under control conditions, after ...
Harrison J M - - 1997
The electroretinogram (ERG) vs perfusion pressure relation was studied in anesthetized rabbits during mechanically induced changes in mean arterial pressure (MAP). After 1 hr of dark adaptation, ERGs were obtained at perfusion pressures from 10 to 95 mmHg with each pressure held for 30-60 sec, and at three levels from ...
Gual A - - 1997
PURPOSE: To analyze the influence of time of storage, the presence of albumin at physiological concentrations, and the perfusion with anisosmotic media on the aqueous humor outflow facility (C) of isolated bovine anterior segments (AS). METHODS: Anterior segments dissected from cow eyes were perfused at a constant pressure of 10 ...
Gralinski M R - - 1997
Evidence is presented that treatment with a highly sulfated low-molecular-weight heparin fraction, LU 51198, protects the ex vivo perfused rabbit heart from human complement-mediated injury. Hearts from male New Zealand White rabbits were perfused under constant flow in the Langendorff mode. After equilibration, normal human plasma was added to the ...
Fujimiya M - - 1997
Since definitive morphological studies showing the luminal release of serotonin have not been reported, we used a perfused system which allows physiological monitoring and biochemical as well as morphological evidence indicating release of serotonin from enterochromaffin cells. Isolated vascularly and luminally perfused rat duodenums exposed to 5-35 cmH2O of luminal ...
Crandall C G - - 1997
During a hyperthermic challenge, skin blood flow (SkBF) increases primarily through activation of the cutaneous active vasodilator system. However, mechanisms through which activation of this system elevates SkBF remain unknown. In this project, we sought to identify whether functional beta-adrenoceptors exist on cutaneous vessels and, if present, whether these receptors ...
Forster B A - - 1997
Uptake of circulating albumin by the aortic wall is greater downstream than upstream of branches in immature rabbits, but the opposite pattern occurs in mature animals. We investigated the role of NO in determining these variations. Descending thoracic aortas of rabbits were cannulated using techniques that avoid depressurization, overstretching, and ...
Tao Z W - - 1997
AIM: To study the cardioprotective effects of oxygen free radicals (OFR) and calcitonin gene-related peptide (OGRP) pretreatment on myocardial damages due to OFR in isolated perfused rat heart. METHODS: The hearts were perfused in a Langendorff mode. OFR were generated by electrolysis of Krebs-Henseleit (K-H) solution. RESULTS: OFR pretreatment reduced ...
Cvetković N - - 1997
In this paper we describe a modified intestinal perfusion technique for investigation of bioadhesion phenomena. This technique is an in vitro method with well standardized experimental conditions which measures the intestinal intraluminal pressure and its oscillation. This also allows the vitality of the intestinal segment used in the experimental to ...
Champion H C - - 1997
Responses to rat (r) adrenomedullin (ADM) and human (h) ADM were compared in the hindlimb vascular bed of the cat under conditions of controlled blood flow. Intra-arterial injections of rADM and hADM in doses of 0.03-1 nmol caused dose-related decreases in hindlimb perfusion pressure. In terms of relative vasodilator activity, ...
Aiuto L T - - 1997
OBJECTIVE: To investigate whether an infusion of recombinant tissue plasminogen activator would dissolve microvascular thromboses and improve organ perfusion in a patient with fulminant meningococcemia. DESIGN: Descriptive case report. SETTING: Fifteen-bed pediatric intensive care unit (ICU) in a university hospital. PATIENT: A 4-month-old male with fulminant meningococcemia, refractory shock, and ...
Todaka K - - 1997
OBJECTIVES: The impact of acute collagen disruption by the disulfide donor, 5,5'-dithio-2-nitrobenzoic acid (DTNB) on ventricular properties was tested in rat hearts. METHODS: Collagen was degraded acutely in 13 isolated, isovolumically contracting rat hearts by perfusion with 1 mM DTNB added to Krebs-Henseleit solution for 1 hour followed by 2-hour ...
Wilson P S - - 1997
Vascular shear stress increases when blood flow or blood viscosity increases or when vessel diameter decreases. In the systemic circulation, shear stress is a potent stimulus for endothelial nitric oxide synthesis. We studied isolated rat lungs to determine whether increasing shear stress increases nitric oxide synthesis in the pulmonary circulation. ...
Rao V - - 1997
BACKGROUND: Improved methods of donor heart preservation may allow for prolonged storage and permit remote procurement. Previous attempts to use oxygenated perfusion circuits during storage have not gained widespread acceptance because they were either too impractical or complicated to use for remote harvest. We hypothesized that collection and perfusion of ...
Heslinga J W - - 1997
If intramyocardial pressure (IMP) is the pressure that causes coronary flow to stop, i.e., "backpressure," then it should be equal to the zero-flow perfusion pressure intercept (Pzf). Therefore we determined Pzf and IMP at zero flow (IMPzf) in papillary muscles suspended isometrically in a bath, superfused with a well-oxygenated Tyrode ...
Cringle S J - - 1997
PURPOSE: A perfusion system for studying the vasoactive properties of the guinea-pig choroid is described. METHODS: The principle of operation is that the vascular resistance of the entire vascular network of an isolated, perfused eye can be monitored by recording the pressure required to deliver a constant flow of perfusate ...
Inserte J - - 1997
To investigate the role of Na(+)-H+ exchange occurring during hypoxia in the genesis of reoxygenation-induced myocardial oedema, isolated perfused rat hearts were submitted to 40 min of hypoxia and 90 min of reoxygenation. The influence of three factors on myocardial water content was analysed according to a 2 x 2 ...
Falck G - - 1997
RATIONALE AND OBJECTIVES: The purpose of this study was to evaluate the role of biophysical factors (viscosity, temperature, osmalality, perfusion pressure, and ionic washout) on cardiac contractility during coronary bolus perfusions. METHODS: Guinea pig hearts were perfused in the osmolality mode at constant and high flow (30 mL/min) and were ...
< 7 8 9 10 11 12 13 14 15 16 17 >