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Results 451 - 500 of 1551
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Tanguay M - - 1997
Recent evidence suggests that newer vasoselective dihydropyridine calcium antagonists are not cardiodepressant and may be useful in the treatment of heart failure. No data are available on the efficacy of clentiazem, a vasoselective benzothiazepine-like calcium antagonist, in this pathological condition. Therefore, our objective was to assess coronary and cardiac sensitivity ...
Graf B M - - 1997
BACKGROUND: 8-ornithine-vasopressin (ornipressin, POR-8) is used as a potent peripheral vasoconstrictor mainly in combination with local anaesthetics. Because ornipressin causes vasoconstriction, any myocardial depressive effects could be caused indirectly by reduced myocardial perfusion secondary to coronary vasoconstriction, or directly by effects on myocardial tissue. METHODS: On isolated guinea pig hearts, ...
Schreiner W - - 1997
Models of coronary arterial trees are generated by the algorithm of constrained constructive optimization (CCO). In a given perfusion area a binary branching network of straight cylindrical tubes is generated by successively adding terminal segments to the growing structure. In each step the site of connection is chosen according to ...
Graf B M - - 1997
8-Arginine vasopressin (AVP) is a powerful coronary vasoconstrictor as well as peripheral vasoconstrictor, but AVP also is reported to have negative cardiac inotropic and chronotropic effects in vitro and in vivo. Our aim was to examine the direct effects of coronary vasoconstriction by AVP on cardiac function and metabolism in ...
Nasa Y - - 1997
A mechanism by which acetylcholine (ACh) may elicit vasoconstrictor response in coronary vessels was studied in rat hearts perfused at a constant flow rate. In spontaneously beating hearts, bolus injections of ACh and carbachol (CCh) produced biphasic changes in coronary perfusion pressure (CPP): a transient increase at the initial period ...
Andreacchi A S - - 1997
Many fungal products are known to possess biological activity towards the mammalian tissues. We studied vasodilating activity in the crude ethanol extract of the dried mycelia of Basidiomycetes sp. YL8006, cultured by submerged fermentation with a complex medium. The activity was assayed using the isolated perfused rat heart in the ...
Puybasset L - - 1997
The effects of intravenous (iv) bolus administrations of bradykinin (0.1-1 microgram.kg-1) on large and small coronary arteries were investigated in seven chronically instrumented conscious dogs. Bradykinin dose-dependently increased heart rate, left ventricular dP/dt max, coronary blood flow and coronary artery diameter and decreased aortic pressure. Subchronic inhibition of the nitric ...
Vigorito C - - 1997
The time course of the effects of intravenous or intracoronary administration of peptide leukotrienes on metabolic parameters and on systemic and coronary hemodynamics was evaluated in 15 patients with normal coronary arteries. Peptide leukotriene C4 (2 nmol given as a bolus intravenous injection) induced an early fall (at 2 min) ...
Damiano B P - - 1996
Thrombin's cellular actions are mediated by a novel G-protein coupled transmembrane receptor. We infused SFLLRN, a peptide that directly activates thrombin receptors, into the left circumflex coronary artery (CFX) of anesthetized dogs to evaluate the cardiovascular effects of thrombin receptor activation in vivo. Intracoronary SFLLRN, 0.9, 9 and 90 nmol/min, ...
Kondo M - - 1996
Our goal was to develop a new method to evaluate coronary flow reserve independent of perfusion pressure by equipping dogs with a Doppler flow probe in the left anterior descending artery. The slope of the linear portion of the velocity-pressure loop in the late diastolic phase was defined as VP ...
Ku D D - - 1996
Recent advances in genetic methods permit the introduction of random and defined mutations into the mouse germ line, producing novel mouse strains, some of which affect the heart and vasculature. A TTR-ANF transgenic strain of mice, which constitutively expresses a fusion gene consisting of the transthyretin promoter and the ANF ...
Chatterjee S - - 1996
A total of 100 patients were studied for the diastolic blood pressure response to treadmill exercise testing. No change in the diastolic pressure or lowering of the pressure was considered normal response. Seventy-four patients had normal and 26 patients had abnormal diastolic blood pressure response. Forty patients underwent coronary angiography. ...
Taggart P - - 1996
BACKGROUND: Mechanisms underlying the initiation of ventricular arrhythmias in ischemia by a premature beat or after a pause remain unclear. The kinetics of electrical restitution, which is the modulation of action potential duration (APD) by an abrupt alteration in cycle length, may be important. METHODS AND RESULTS: We recorded one ...
Drinkhill M J - - 1996
1. We previously reported that, although stimulation of coronary arterial baroreceptors results in reflex vasodilatation of a magnitude and a time course similar to that seen in response to carotid baroreceptor stimulation, the vasoconstriction that occurs when the stimulus to coronary baroreceptors is removed develops more slowly. We now report ...
García J L - - 1996
The role of endothelin ETA and ETB receptors as well as of nitric oxide (NO) and prostanoids in the effects of endothelin-1 on the coronary circulation was studied in anesthetized goats. Where blood flow in the left circumflex coronary artery (coronary blood flow) (electromagnetically measured), systemic arterial pressure, left ventricle ...
Deakin C D - - 1996
We describe two patients who both suffered a cardiac arrest whilst maintained on an intra-aortic balloon pump. In an attempt to improve coronary and cerebral blood flow during cardiopulmonary resuscitation, the intra-aortic balloon was inflated to occlude the descending aorta and preferentially direct blood to the cerebral and coronary circulation. ...
Baan J J - - 1996
In the externally perfused coronary bed of the isolated heart, LV elastance (Elv) rather than LV pressure (Plv) appears to be the major factor responsible for systolic coronary flow reduction, although effects of both have been demonstrated. However, normal perfusion in the presence of intact autoregulation in the heart in ...
Vacca G - - 1996
BACKGROUND: Gallbladder distension in anesthetized pigs reflexly increases heart rate and arterial pressure by means of afferent vagal pathways and efferent sympathetic mechanisms. The effect of such distension on the coronary circulation is unknown. The present study was undertaken to determine whether gallbladder distension primarily causes reflex changes in left ...
Doi Y - - 1996
To clarify the effect of left ventricular (LV) diastolic pressure on the coronary pressure-flow relation in humans, the instantaneous diastolic coronary pressure-Doppler flow velocity relation was analyzed at rest and during papaverine-induced maximal vasodilation in 15 patients with angiographically normal coronary arteries. The values for slope (alpha PF) and zero-flow ...
Grauer S E - - 1996
The development of echo contrast agents that can provide reliable opacification of the myocardium after intravenous injection is an important advancement for the clinical application of contrast echocardiography. In this study, the hemodynamic effects and echocardiographic characteristics of a new lipid-fluorocarbon echo contrast agent, Aerosomes MRX 115 (ImaRx Pharmaceutical Corp., ...
Siebes M - - 1996
The influence of passive vasomotion on the pressure drop-flow (delta P-Q) characteristics of a partially compliant stenosis was studied in an in vitro model of the coronary circulation. Twelve stenosis models of different severities (50 to 90 percent area reduction) and degrees of flexible wall (0 to 1/2 of the ...
de Bruyne B - - 1996
BACKGROUND: To assess coronary lesion severity in the catheterization laboratory, several guide wire-based methods have been proposed. The purpose of the present study was to compare the feasibility and the reproducibility of coronary flow velocity reserve (CFVR), instantaneous hyperemic diastolic velocity-pressure slope index (IHDVPS), and pressure-derived myocardial fractional flow reserve ...
Quail A W - - 1996
1. Baroreflex responses to changes in aortic pressure were measured simultaneously in three main coronary regions of awake dogs. 2. Pulsed Doppler flow probes were mounted at prior surgery on the right, circumflex and anterior descending coronary arteries; the animals were placed in complete heart block and the left ventricle ...
Niimi Y - - 1996
OBJECTIVES: To assess the effect of intravenous nitroglycerin (NTG) on segmental wall motion abnormalities (SWMAs) and global ventricular function after anesthetic induction in patients undergoing coronary artery bypass grafting (CABG). DESIGN: Prospective study. SETTING: University hospital. PARTICIPANTS: Twenty patients scheduled for elective CABG. INTERVENTIONS: Patients demonstrating SWMAs in at least ...
Recchia F A - - 1996
Acute increases in arterial pulsatile load imposed on the left ventricle can increase coronary flow without commensurate changes in myocardial oxygen consumption. One explanation is that augmenting pulsatile perfusion at the same mean pressure itself stimulates flow by releasing endothelium-mediated vasorelaxant factors such as NO. The present study tested this ...
Macho P - - 1996
OBJECTIVE: In vitro experiments have shown that an electric field changes coronary vascular resistance (CVR) tone and damages the vascular endothelium. The effect of transthoracic electric current in dogs on the vasodilatory responses mediated through the endothelium and reactive hyperemia were studied. The manner of delivery of the electric current ...
Cho H - - 1996
A variety of compounds having a benzopyran such as levcromakalim generally exhibit potent antihypertensive activity. During extensive investigations aimed toward identifying K+ channel openers having selective coronary vasodilation without potent hypotensive and tachycardiac effects, we synthesized a series of 3,4-dihydro-2H-1-benzopyran-3-ol derivatives modified at positions 2, 4, and 6 in the ...
Gutterman D D - - 1996
Coronary vasoconstriction is a component of the baroreflex response to bilateral carotid occlusion. The central pathways responsible for this reflex constriction are incompletely understood, but previous studies show that activation of parabrachial nucleus (PBN) elicits coronary vasoconstriction and that PBN shares prominent anatomic connections with other central baroreflex centers, including ...
Crystal G J - - 1996
RATIONALE AND OBJECTIVES: The study was performed to clarify the mechanisms underlying contrast-induced coronary vasodilation. METHODS: The left anterior descending coronary artery of 14 open-chest dogs was perfused at constant pressure. Coronary blood flow (CBF) was measured electromagnetically and used to calculate myocardial oxygen consumption (MVO2). Responses were evaluated during ...
Dijkman M A - - 1996
Increased cardiac perfusion results in increased oxygen consumption (VO2) and increased contractility (Gregg phenomenon) in the isolated heart. We investigated whether these two aspects of the Gregg phenomenon are related to coronary flow or arterial pressure. Coronary flow and, thus, arterial pressure were changed in the reference state and during ...
Rynning S E - - 1996
The effect of afterload during regional ischaemia on myocardial stunning was studied in 15 pentobarbital anaesthetized cats. 10 min occlusion of the left anterior descending artery (LAD) was followed by 60 min of reperfusion. Afterload was decreased by intravenous infusion of nitroglycerine 3-8 micrograms kg-1 min-1 in group I (n ...
Bosi S - - 1996
OBJECTIVE: To assess the response of internal mammary artery (IMA) flow of hypertensive hearts to nitroprusside infusion. METHODS: Fifteen patients were studied with a high-frequency duplex Doppler probe from the supraclavicolar approach. All the patients had undergone coronary artery bypass surgery with an IMA graft into the left anterior descending ...
Voelker W - - 1996
Perfusion balloon catheters are designed to provide continuous transcatheter blood flow and thereby reduce myocardial ischemia during coronary angioplasty. To compare the transcatheter flow rates of active and passive (auto-) perfusion catheters, a well-controlled experimental study was performed in a circulation model that duplicates the phasic, predominantly diastolic flow pattern ...
Mitsugi M - - 1996
OBJECTIVE: We compared the effects of diastolic coronary sinus pressure elevation due to synchronized retroperfusion (SRP) with systolic coronary sinus pressure elevation due to coronary sinus occlusion on the coronary pressure-flow relationship under similar mean coronary sinus pressure values. METHODS: Using isolated, perfused canine hearts, coronary perfusion of the left ...
Allaart C P - - 1996
We studied the impeding effect of cardiac muscle contraction on coronary arterial inflow in six isolated, perfused papillary muscles of the rat. Special attention was given to the effect of changes in muscle length and contractility on flow impediment in systole. Contractility was changed by resumption of pacing after a ...
Shi G G - - 1996
AIM: To study the effect of phencyclidine (Phe) on dog coronary artery. METHODS: Contraction of spiral strips of dog coronary artery in bioassay and coronary artery blood flow (CBF) using electromagnetic flowmeter on anesthetized dogs were observed. RESULTS: Phe 0.1-100 mumol.L-1 induced contraction of strips in a concentration-dependent manner. Dextromethorphan ...
Motz W - - 1996
To date, no clinical study shows an improvement in coronary flow reserve due to long-term antihypertensive therapy. in view of the contribution of the renin-angiotensin system to the process of hypertensive remodeling of the heart and coronary circulation, angiotensin-converting enzyme (ACE) inhibitors might act as cardioreparative drugs in arterial hypertension. ...
Okada K - - 1996
BACKGROUND: The University of Wisconsin solution has been proven to be effective for prolonged heart preservation. However, 24-hour heart preservation by simple cold immersion in University of Wisconsin solution has been disappointing. We have performed hypothermic low-pressure continuous coronary perfusion with oxygenated University of Wisconsin solution for experimental prolonged heart ...
van Wezel H B - - 1996
BACKGROUND: The rate of adaptation of coronary blood flow in response to stepwise changes in heart rate (HR) has been extensively studied in dogs and goats to improve our understanding of the dynamics of coronary regulation processes and their pathophysiology and to obtain time constants for mathematical modeling of the ...
Huang Y F - - 1996
The rapid intravenous administration of 10 ml of sterile water or hypotonic saline to five conscious sheep induced substantial adverse haemodynamic effects lasting 10 to 20 seconds. They included reductions in cardiac output (to 44 per cent of the baseline value measured in the 30 seconds before the injection), arterial ...
Knot H J - - 1996
1. The hypothesis that inward rectifier K(+) channels are involved in the vasodilatation of small coronary and cerebral arteries (100-200 microm diameter) in response to elevated [K+]o was tested. The diameters and membrane potentials of pressurized arteries from rat were measured using a video-imaging system and conventional microelectrodes, respectively. 2. ...
Kass D A - - 1996
BACKGROUND: [corrected] Age is an independent risk factor for increased mortality from ischemic heart disease. Arterial stiffening with widening of the pulse pressure may contribute to this risk by exacerbating cardiac dysfunction after total coronary artery occlusion. METHODS AND RESULTS: To test the above hypothesis, 14 open-chest dogs underwent surgery ...
Bélichard P - - 1996
1. Mongrel dogs were chronically instrumented with an intra-aortic catheter, a Königsberg intraventricular pressure transducer and a Döppler flow probe around the left coronary artery. After ganglionic blockade with hexamethonium, the cardiovascular effects of bradykinin B1 and B2 receptor agonists, des-Arg9-bradykinin and bradykinin (BK), were investigated in the presence and ...
Schaefer S - - 1996
BACKGROUND: Endogenous production of bradykinin (BK) has been postulated to cause hemodynamic changes and cardiac pain during myocardial ischemia, presumably because of the stimulation of cardiac afferent fibers. METHODS: To test the hypothesis that BK results in cardiac reflex responses and can cause the sensation of angina, 10 patients with ...
Hiller K H - - 1996
Myocardial perfusion measurement with colored microspheres may become an alternative for radioactive microsphere techniques. We use and validate a spectrophotometric method that has been previously established for large animals in the isolated perfused rat heart. The perfusion system was adapted for use in a NMR microscope. Hearts were perfused with ...
Nanto S - - 1996
Coronary pressure flow (P/F) relationship has been investigated mainly from the viewpoint of coronary resistance. However, recent experimental evidence suggests that the zero flow pressure intercept (Pzf) provides important characteristics of coronary circulation. Although Pzf is likely to provide meaningful information about characteristics of coronary circulation, no data are available ...
Miao L - - 1996
1. Systemic and coronary haemodynamics were measured in 6 Yorkshire swine and 6 Yucatan miniature swine under isoflurane anaesthesia to investigate the influence of cocaine following its intravenous administration at 1, 3 and 7 mg kg-1. 2. Cocaine in Yorkshire swine decreased mean arterial pressure and rate pressure product (systolic ...
Arkonac B M - - 1996
The systemic and coronary hemodynamic effects of the nitrovasodilator, pirsidomine, were compared with SIN-1, nitroprusside, and nitroglycerin. Four groups consisting of 32 experiments were performed in 17 conscious dogs chronically instrumented for measurement of aortic and left ventricular pressure, left ventricular dP/dtmax, diastolic coronary blood flow velocity, cardiac output, and ...
Kostić M M - - 1996
The aim of this study was to evaluate the role of endogenous histamine in the regulation of reactive hyperaemia (RH) and coronary autoregulation in isolated rat hearts. The basal release of cardiac histamine (perfusion pressure 60 cm H2O) amounted to 100-200 pmol/min/g wt. During the first 15 s following 30 ...
Ogonowska-Kobusiewicz M - - 1996
The aim of this study was to investigate the effect of Iloprost (Schering AG), a stable prostacyclin analogue, on the intensity of thiobarbituric acid-reactive substances (TBARS), conjugated diene and hydroperoxide production in ischaemic dog myocardium. Adult male mongrel dogs were divided into groups as follows: A = sham/operated group, B ...
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