Search Results
Results 301 - 350 of 817
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Amanullah A M - - 1997
Whether adenosine myocardial perfusion single-photon emission computed tomography (SPECT) remains accurate for detecting coronary artery disease (CAD) in the absence of peripheral hemodynamic changes is unknown. To assess the hemodynamic correlates of perfusion defects, we studied 222 consecutive patients (age 71 +/- 11 years) without prior myocardial infarction or revascularization ...
Otomo J - - 1997
Nitric oxide (NO) and adenosine are important mediators in the regulation of coronary vascular tone and are released into the interstitium from the vascular endothelium and myocardium, respectively. The roles of these autacoids in the regulation of coronary flow in the basal and reactive hyperemic states were examined in Langendorff ...
Xia Z F - - 1997
To test the hypothesis that energy deficits and intracellular ion derangements may be the cellular basis for intrinsic myocardial dysfunction in rats after burn trauma, we examined ATP metabolism, intracellular pH, sodium, and mechanical performance simultaneously in perfused beating hearts from sham burn or burned rats (43% TBSA, 3 degrees ...
Vanelli G - - 1997
The effects of blockading the ATP-sensitive potassium channel (K+ATP channels) on endotoxin-induced vascular derangements was studied. Escherichia coli endotoxin was infused (20 micrograms/kg per h) intravenously for 180 min into anaesthetized, mechanically ventilated, indomethacin-treated pigs. After 150 min of endotoxaemia, glibenclamide (a K+ ATP channel blocker) was infused intravenously at ...
Tomera J F - - 1997
This study examined the effect of N-ethylmaleimide (NEM, 10(-7) M) on agonist-induced contraction and the relaxation following drug-washout, of vascular smooth muscle (VSM) segments derived from hypertensive rabbits. Mean blood pressure increase was produced either by renal constriction plus contralateral nephrectomy, or by cadmium acetate ingestion. Freely-ionized calcium (45Ca)flux, cyclic ...
Macedo M P - - 1997
Our objective was to determine the vasodilator effect of adenosine and isoproterenol on the hepatic artery (HA) and superior mesenteric artery (SMA) before and after blockade of nitric oxide (NO) production to evaluate the possibility of organ specificity. Vascular circuits supplied blood flow to the liver or intestine in cats ...
Elias A N - - 1997
1. The effect of high-dose adenosine administration on atrial natriuretic peptide (ANP) and antidiuretic hormone (ADH) release is not completely understood, and data concerning the effect of adenosine on renal and systemic hemodynamics in the pig are lacking. Measurements of central hemodynamics, renal blood flow and urine production were made ...
Tian R - - 1997
Sarcomere relaxation depends on dissociation of actin and myosin, which is regulated by a number of factors, including intracellular [MgATP] as well as MgATP hydrolysis products [MgADP] and inorganic phosphate [Pi], pHi, and cytosolic calcium concentration ([Ca2+]c). To distinguish the contribution of MgADP from the other regulators in the development ...
Sabates B L - - 1997
The following experiments were conducted to determine whether, and the mechanisms through which, endogenous peptides alter coronary artery blood flow. Ultrasonic transit time probes were placed around the ascending aorta and left anterior descending coronary artery in groups of anesthetized, open-chest dogs. A Millar pressure catheter monitored left ventricular developed ...
Rongen G A - - 1997
Adenosine increases heart rate and sympathetic nerve activity reflexively in conscious humans through several mechanisms. The purpose of this study was to assess the relative contributions of arterial baroreceptor unloading, carotid chemoreceptor stimulation, and other adenosine-sensitive afferent nerves to these responses. In 12 healthy men, the effect on blood pressure, ...
Buijs E J - - 1997
The authors present a case of severe electrolyte and acid-base disturbances after administration of sorbitol. The rate of sorbitol infusion was in excess of the stated maximum safe infusion rate in parenteral nutrition. Sorbitol was used for treating raised intracranial pressure. The mechanisms of sorbitol metabolism leading to hyperlactacemia, lactic ...
Chang H Y - - 1997
The effects of glibenclamide (GLB), a specific blocker of ATP-sensitive potassium (KATP) channels, and tetraethylammonium (TEA) on modulating the regulation of diaphragmatic microcirculation were assessed in anesthetized mechanically ventilated rats. With bicarbonate-buffered Ringer solution continuously suffusing the left hemidiaphragm, microcirculatory blood flow was recorded by laser-Doppler flowmetry (QLDF). Hemorrhagic hypotension ...
Forrest E H - - 1997
BACKGROUND: Adenosine is a potent vasoactive substance that may be responsible for mediating the altered haemodynamics found in patients with cirrhosis. AIM: The administration of oral theophylline was used to investigate the effect of adenosine receptor antagonism upon the circulation of patients with cirrhosis. METHODS: Twenty eight patients were given ...
Van Way C W - - 1996
Certain tissues are known to be susceptible to shock-induced damage: liver, small bowel mucosa, and small bowel wall. This study was done to assess the changes in adenine nucleotides induced by hemorrhagic shock. Male Sprague-Dawley rats (n = 21; 300-350 g) were anesthetized with sodium pentobarbital (50 mg/kg, ip) and ...
Schlüter H - - 1996
1. Diadenosine phosphates were isolated from platelets, adrenal gland and autonomic nerves. The presence of diadenosine phosphates in storage pools releasable into the circulation suggests an important role in the control of blood pressure, and potentially to a modulation of the actions of catecholamines. 2. Besides a role of the ...
Jasmin G - - 1996
Previous studies on the heart necrotizing process at early stages of the hamster polymyopathy have led us to believe that this hereditary disease derives from a defective transmembrane ion flux resulting in myocardial Ca2+ over-load. On the other hand, certain K+ ATP channel openers were shown to prevent cytosolic Ca2+ ...
Griffiths T L - - 1996
BACKGROUND: In normal subjects intravenous adenosine infusion has been shown to stimulate ventilation with a consequent fall in arterial partial pressure of carbon dioxide (Paco2), probably by an action on the carotid bodies. The objective of this study was to determine whether the increase in Paco2 seen when patients with ...
van der Voort P H - - 1996
For calculation of fractional flow reserve (FFR), simultaneous registration of both aortic pressure (Pa) and transstenotic distal coronary pressure (Pd) is necessary at steady-state maximum coronary hyperemia. The aim of the present study was to compare the maximum transstenotic gradient (delta Pmax) and pressure-derived myocardial fractional flow reserve (FFRmyo), observed ...
Hara A - - 1996
The effect of dilazep, a potentiator of the adenosine-mediated effects, on the palmitoyl-L-carnitine (PALCAR)-induced mechanical derangement was studied in the isolated rat heart and compared with that of K-7259, a dilazep derivative having less potentiating action on the adenosine-mediated effects. The heart was perfused aerobically by the Langendorff's technique at ...
Chung Y - - 1996
Nitrite oxidation of oxymyoglobin in perfused rat myocardium under nonlimiting oxygen produces a detectable 1H nuclear magnetic resonance metmyoglobin (metMb) signal at -3.9 ppm. When the myocardium is perfused with < 10 mM nitrite, the 1H nuclear magnetic resonance MbO2 gamma CH3 Val E11 signal does not change intensity and ...
Qiu Y - - 1996
We used metabolic, enzymatic, and functional end points to compare the protective properties of continuous warm and intermittent cold cardioplegic infusion in isolated, blood-perfused rat hearts. After excision, hearts (n = 12 per group) were preserved for 3 hours by one of the following cardioplegic procedures: (1) continuous infusion of ...
Huxley V H - - 1996
We have developed a new method to quantify solute flux per unit surface area and concentration gradient (JS/S delta C) from arterioles isolated from pig hearts. The apparent permeability (Ps) was assessed from measurements of JS/S delta C for two proteins, alpha-lactalbumin (alpha-lactalb) and porcine serum albumin (PSA), labeled with ...
Beyer M E - - 1996
Positive inotropy of endothelin-1 (ET-1), which has already been described in vitro, has not been detected in vivo. Combination with vasodilators has been shown to unmask a positive inotropic effect of ET-1. The ET-induced direct positive inotropy, which seems to be mediated by endothelinB (ETB) receptors, is antagonized in vivo ...
Karimi A - - 1996
To examine a possible metabolic regulatory role for adenosine, infusions of adenosine and adenosine deaminase were given to 11 near-term fetal sheep during the simulation of birth in utero. Fetal arterial blood gases, the concentration of a number of metabolites, insulin, and whole body O2 consumption (VO2) were measured. After ...
Van Raemdonck D E - - 1996
BACKGROUND: If lungs could be retrieved for transplantation from non-heart-beating cadavers, the shortage of donors might be significantly alleviated. METHODS: Adenosine triphosphate (ATP) and hypoxanthine levels were measured postmortem in rabbit lungs comparing deflation (group 1), ventilation with room air (group 2), inflation with room air (group 3), ventilation with ...
Headrick J P - - 1996
OBJECTIVE: Adenosine, derived from hydrolysis of 5'-AMP, may be involved in coupling coronary blood flow to cardiac function and metabolism. The purpose of this study was to measure interstitial fluid (ISF) adenosine and 5'-AMP levels, and cytosolic 5'-AMP in in situ rabbit heart during beta-adrenergic stimulation. METHODS: Isoproterenol was infused ...
Tang Y Y - - 1996
We test the hypothesis that the heart and arteries enlarge with increased cardiac output (CO) during development and volume overload. Transparent albino tadpoles of Xenopus laevis at stages 43-50 were anesthetized in 0.3-0.5 mM benzocaine. Areas and radii [maximum and minimum radius (Rmax and Rmin, respectively)] of the ventricle were ...
Taillefer R - - 1996
BACKGROUND: Both dipyridamole and adenosine are widely used as pharmacologic stressors with 201Tl imaging for detection of coronary artery disease. The purpose of this study was to compare dipyridamole and adenosine 201Tl imaging directly in patients with angiographically proved coronary artery disease. METHODS AND RESULTS: Fifty-four patients were submitted to ...
Mathoôt R A - - 1996
1. The purpose of the present study was to develop an experimental strategy for the quantification of the cardiovascular effects of non-selective adenosine receptor ligands at the adenosine A1 and A2a receptor in vivo. 2-Chloroadenosine (CADO) was used as a model compound. 2. Three groups of normotensive conscious rats received ...
Kaplan L J - - 1996
In postischemia hearts, cytoplasmic creatinine kinase (CK) inactivation resulting from toxic oxygen metabolite injury may lead to bioenergetic and mechanical dysfunction. This study determines the relationship between CK activity, mechanical function, and bioenergetics during reperfusion (RP) after a reversible ischemic injury. Rat hearts pretreated after 12 hr without (CTRL) or ...
Matherne G P - - 1996
We examined myocardial responses to reduced arterial PO2 and the role of endogenous adenosine in constant-pressure perfused hearts from immature (Imm) and mature (Mat) rabbits. During normoxia, coronary flow and myocardial O2 consumption were similar in both groups. With moderate hypoxia, coronary perfusate flow increased by 125 +/- 16% in ...
Rongen G A - - 1996
ATP is coreleased with norepinephrine from sympathetic nerve endings and subsequently broken down to adenosine. In animal preparations, adenosine can inhibit norepinephrine release by stimulation of presynaptic receptors. We tested this feedback mechanism in humans by using a specific nucleoside transport inhibitor (draflazine) as a pharmacological tool to allow accumulation ...
Godart H - - 1996
1. Pressure induced a 4- to 5-fold stimulation of the residual (i.e. oubain-bumetanide insensitive) 86Rb+ influx across the human red cell membrane. This enhancement showed a broad pHo dependence with a maximum stimulation around pHo 7. 2. At atmospheric pressure, the protein kinase inhibitors staurosporine and chelerythrine stimulated a normally ...
Harrison G J - - 1996
Exogenous adenosine causes a monophasic dilation of the coronary vessels in paced, perfused rat heart preparations. Because levels of endogenous adenosine in paced hearts may mask the presence of high potency adenosine receptors, we have developed a method to measure coronary vascular responses in a potassium-arrested heart. Hearts from adult ...
Valen G - - 1996
Adenosine is an endogenous cardioprotective substance. The present study examines whether exogenous adenosine attenuates cardiac injury induced by oxidative stress. Rat hearts (Langendorff model) were perfused with H2O2 (180 microM) for 10 min, then recovered for 60 min (n = 10). In other groups adenosine 55 microM, 11 0 microM, ...
Tsanev R - - 1996
A dosed mechanical pressure of 12.5 kg/cm2 applied for 1 min on depilated mouse skin did not cause cellular death or visible alterations of the cellular ultrastructures. However, it had a strong effect on the mitotic cycle of the epidermal cells-stimulating the cells to enter the mitotic cycle and temporarily ...
Mallet R T - - 1996
OBJECTIVE: We have previously demonstrated that myocardium is capable of down-regulating its O2 requirements and thus avoiding ischaemia when O2 supply is limited. The present study tested the hypothesis that endogenous adenosine produced this protective response when O2 supply was decreased by moderate coronary hypoperfusion or moderate coronary hypoxaemia. METHODS: ...
Thomas T - - 1996
The effects of microinjections of adenosine and an adenosine receptor antagonist into the rostral ventrolateral medulla (RVLM) on the cardiovascular changes associated with the defence reaction were investigated in anaesthetized rats. Responses to electrical and chemical stimulation in RVLM were determined in alpha-chloralose-anaesthetized, paralysed and artificially ventilated rats. Microinjections of ...
Poizat C - - 1996
The purpose of this study is to determine the relationship between cardiac performance and energy production in isolated rat heart when heart function is modified either by calcium concentration or by oxygen partial pressure (PO2), and to evaluate the relative contribution of glycolytic ATP. Hearts are perfused at a constant ...
Rossi A - - 1996
OBJECTIVE: When the myocardium is subjected to a chronic overload, it enlarges and a major restructuring of all organelles and cellular functions occurs. The changes occurring at the level of the contractile apparatus are well documented; less is known about the alterations in the energy status of the hypertrophied cardiomyocyte. ...
Fullerton D A - - 1996
OBJECTIVE: The purpose of this study was to examine and compare the systemic and pulmonary hemodynamic effects of a central venous infusion of adenosine in cardiac surgical patients. DESIGN: Prospective; each subject served as his/her own control. SETTING: University Hospital and Veteran's Affairs Medical Center. PATIENTS: Ten cardiac surgical patients ...
Kokita N - - 1996
BACKGROUND: Oxygen-derived free radicals are involved in tissue damage during myocardial ischemia and reperfusion. Recent in vitro studies have demonstrated that a beneficial effect of propofol lies on its free radical scavenging properties. The current study, therefore, examined whether propofol is effective against the mechanical and metabolic damage induced by ...
Hara A - - 1995
The effect of NKH477 (6-(3-dimethylaminopropionyl)forskolin hydrochloride, CAS 138605-00-2), a novel water-soluble forskolin derivative, on the energy metabolism of the heart was examined and compared with that of dobutamine. The isolated rat heart was perfused with Krebs-Henseleit bicarbonate buffer with a gas mixture containing 95% O2 + 5% CO2 according to ...
Ramsey M W - - 1995
BACKGROUND: Vascular tone is a determinant of conduit artery distensibility. The aim of this study was to establish whether endothelium-derived relaxing factor (EDRF) influences the distensibility of conduit arteries and whether endothelium-mediated increases in distensibility are impaired in chronic heart failure (CHF). METHODS AND RESULTS: Conduit artery distensibility was measured ...
Gilbert E M - - 1995
STUDY OBJECTIVES: We measured the individual and combined effects of the beta-agonist dobutamine and the phosphodiesterase inhibitor enoximone both in vitro and in vivo in the failing human heart. DESIGN: This was an unblinded, prospective study. SETTING AND PATIENTS: The in vitro measurements were performed on 20 hearts obtained from ...
Constantin-Teodosiu D - - 1995
1. The present experiment was undertaken to investigate: (a) the effect of nitric oxide synthase (NOS) inhibition, mediated by oral supplementation of the NOS inhibitor, NG-nitro-L-arginine methyl ester (L-NAME), on measures of myocardial energy metabolism and function: (b) the effect of oral creatine supplementation on these variables, in the absence ...
Randall M D - - 1995
1. The roles of adenosine 5'-triphosphate (ATP)-sensitive potassium channels (KATP) and endogenous adenosine in the regulation of coronary flow have been assessed in the isolated, buffer-perfused heart of the rat. 2. In the presence of glibenclamide 10 microM there was a significant (P < 0.001) reduction in coronary flow from ...
Barlow R B - - 1995
1. 4-Diphenylacetoxy-N-cyclohexylmethyl-piperidine HCl (hexahydro-benz-4DAP) is more active as an antagonist of carbachol at receptors in guinea-pig isolated ileum, log K (pA2) = 6.64 +/- 0.14 (s.e. 7 results), than at receptors in guinea-pig isolated atria, log K = 5.43 +/- 0.14 (7). In the presence of neostigmine bromide (0.2 microM) ...
Fransen R - - 1995
Adenosine infusion is associated with natriuresis as well as antinatriuresis. The physiologic significance of these opposite effects is unknown but may have to do with different conditions of ischemia, in which adenosine accumulates. These effects were characterized in the rat. First, intrarenal and systemic infusions within one animal were performed. ...
Armiger L C - - 1995
Inorganic phosphate (Pi) accumulates extremely rapidly in ischaemic heart muscle and intracellular binding of this metabolite may account for the precipitous loss of function seen at the onset of severe ischaemia. We have used 31P-NMR spectroscopy to measure the free cytosolic [Pi] and chemical assay techniques to measure total tissue ...
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