Search Results
Results 451 - 500 of 931
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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 ...
Hoffenberg E F - - 1995
BACKGROUND: Retrograde normothermic blood cardioplegia has been shown to provide myocardial protection during certain bypass procedures. However, a number of animal studies have shown less than optimal myocardial protection with this technique. METHODS: Isolated, beating porcine hearts were perfused antegradely (aortic root pressure = 75 to 95 mm Hg) for ...
Mathôt R A - - 1995
The purpose of the present study was to quantify the in vivo potency of the selective adenosine A2a antagonist CSC [8-(3-chlorostyryl)caffeine]. Four groups of conscious, normotensive rats received a continuous i.v. infusion of 0, 6, 12 and 24 micrograms/min/kg of CSC. During a steady-state infusion of CSC, the animals received ...
Mathôt R A - - 1995
1. The purpose of the present study was to quantify the cardiovascular effects of the 2'-, 3'-, 5'-deoxyribose analogues of the selective adenosine A1 receptor agonist, N6-cyclopentyladenosine (CPA) in vivo. The blood concentration-effect relationships of the compounds were assessed in individual rats and correlated to their receptor binding characteristics. 2. ...
Acevedo C G - - 1995
Uptake and metabolism of adenosine by human placenta were studied using the single-circulation paired-tracer technique. When isolated cotyledons were perfused through the fetal (basal) circulation at mean pressures of 36 +/- 3.3 mmHg and mean flow rates of 6.6 +/- 0.3 ml/min the maximal [3H]adenosine uptake was 51.3 +/- 3.9 ...
Bakker S J - - 1995
Cardiovascular beriberi is a syndrome caused by thiamine deficiency and characterized by systemic vasodilatation, heart failure and lactic acidosis. The occurrence of heart failure and vasodilatation is yet unexplained: neither theoretical nor experimental data are known. In this article, it is suggested that a fall of cellular ATP levels causes ...
Pearse D B - - 1995
The use of microspheres to measure tissue blood flow requires that the microspheres themselves do not alter regional arterial tone. To determine whether microspheres affected bronchial artery resistance, we cannulated and perfused the bronchial artery in anesthetized sheep. In seven sheep, the change in bronchial artery pressure at constant flow ...
Torielli L - - 1995
Alterations in energy metabolism, reduced fatty acid oxidation, and cardiac carnitine content have been implicated in the evolution from compensated to decompensated cardiac hypertrophy. We determined high-energy nucleotide levels in hypertrophied quiescent cardiomyocytes isolated from rat hearts 4 weeks after banding of abdominal aorta. In hypertrophied quiescent cardiomyocytes, a decrease ...
Zhang J - - 1995
BACKGROUND: This study tested the hypothesis that 31P nuclear magnetic resonance (NMR)-detectable 2-deoxyglucose (2DG) uptake is increased in chronically pressure-overloaded hypertrophied left ventricular myocardium. METHODS AND RESULTS: 31P NMR spectroscopy was used to determine the transmural distribution of high-energy phosphate levels and 2-deoxyglucose-6-phosphate (2DGP) accumulation during intracoronary infusion of 2DG ...
Ide T - - 1995
BACKGROUND: Diaphragmatic fatigue causes respiratory failure, for which aminophylline has been used as therapy. Because the mechanism of action of aminophylline in reversing diaphragmatic fatigue is unclear, we used in vivo 31P magnetic resonance spectroscopy (MRS) to determine the relation between diaphragmatic activation, force output, and aerobic metabolism. METHODS: Bilateral ...
Appel S - - 1995
1. The purpose of this investigation was to develop a pharmacokinetic-pharmacodynamic model for the interaction between an adenosine A1 receptor agonist and antagonist in vivo. The adenosine A1 receptor agonist, N6-cyclopentyladenosine (CPA) and the antagonist, 8-cyclopentyltheophylline (CPT) were used as model drugs. The CPA-induced reduction in mean arterial pressure and ...
Nussbacher A - - 1995
BACKGROUND: Continuous intravenous administration of adenosine to humans often results in a paradoxical rise in pulmonary capillary wedge pressure (PCWP), whereas arterial resistance is lowered and cardiac output and heart rate increase. This is believed to be due to diastolic stiffening of the ventricle or to a negative inotropic effect. ...
Fremes S E - - 1995
Adenosine pretreatment has been shown to be beneficial in several models of ischemia-reperfusion. We wished to evaluate whether adenosine pretreatment is cardioprotective for prolonged cardiac storage and whether the presence of adenosine in the storage media affects the results. Isolated rodent hearts were obtained from Sprague-Dawley rats, mounted on a ...
Schüssler M - - 1995
The influence of the main flavonoids from Crataegus species (hawthorn, Rosaceae) on coronary flow, heart rate and left ventricular pressure as well as on the velocity of contraction and relaxation was investigated in Langendorff perfused isolated guinea pig hearts at a constant pressure of 70 cmH2O. Drug action was evaluated ...
Selldén H - - 1995
We describe a child with a localised pelvic neuroblastoma and a hypertensive crisis during the first weeks of life due to elevated systemic norepinephrine of tumoural origin. In spite of treatment with high doses of alpha-blockers, blood pressure did not respond fully and the boy had a very unstable circulation. ...
Aksut S V - - 1995
Systolic blood pressure typically decreases during adenosine infusion because of stimulation of A2b receptors, resulting in systemic vasodilation. This study examined the results of adenosine single photon emission computed tomography (SPECT) thallium-201 imaging in patients who did not show such a decrease in blood pressure during peak adenosine effect (nonresponders). ...
Decking U K - - 1995
The decreased contraction amplitude of isolated cardiac myocytes from guinea pigs exposed to lipopolysaccharide (LPS) was reported to be partially reversed by nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide synthase (NOS) [Brady, et al., Am. J. Physiol. 263 (Heart Circ. Physiol. 32): H1963-H1966, 1992]. We have tested the ...
Gao Z P - - 1995
OBJECTIVE: The aim was to test the role of interstitial adenosine in protective downregulation of myocardial energy demand during myocardial hibernation. METHODS: Isolated working guinea pig hearts, perfused with glucose fortified Krebs-Henseleit, were subjected to 60 min global low flow ischaemia followed by 30 min reperfusion. Left ventricular performance was ...
Silva P H - - 1995
OBJECTIVE: The objectives were to determine the effects of the adenosine deaminase inhibitor pentostatin (deoxycoformycin) on interstitial fluid (ISF) adenosine before, during, and after myocardial ischaemia and to ascertain whether augmented endogenous ISF adenosine reduces myocardial infarction. METHODS: Untreated anaesthetised dogs (n = 11) were compared to dogs treated with ...
Ponce-Hornos J E - - 1995
Heat production and isovolumetric pressure development (P) were measured simultaneously in the arterially perfused rat ventricle. The time course of the calorimetric signal that follows a contraction could be decomposed into four components of energy released. Three of these components (H1, H2, and H4) were pressure independent, only H3 correlated ...
Laghi Pasini F - - 1995
1. The hypothesis that endogenous adenosine could play a role in the haemodynamic response to L-arginine is investigated. 2. The study has been divided into two parts. The first part was a single blind, randomized, placebo-controlled study in which L-arginine i.v. infusion (0.07 mmol/kg per min) in five healthy volunteers ...
Raschke P - - 1995
OBJECTIVE: The aim was to establish whether polymorphonuclear neutrophils can, by themselves, elicit depression of postischaemic heart function immediately after short periods of ischaemia, and to examine the involvement of endogenous adenosine and platelet activating factor (PAF) in the observed phenomena. METHODS: Isolated buffer perfused guinea pig hearts performing pressure-volume ...
Holmes G - - 1995
This study was designed to investigate effects of perfusate oxygenation and maturation on coronary flow (CF), interstitial transudate adenosine (ITA) and coronary effluent adenosine (CEA) in isolated rabbit hearts. Hearts were paced at a fixed rate and were perfused under constant pressure at two different levels of perfusate oxygenation: baseline ...
Johnston D L DL Division of Cardiovascular Diseases, Mayo Clinic Rochester, MN - - 1995
To compare the hemodynamic responses and the adverse effects associated with two coronary vasodilators used for pharmacologic stress testing. We retrospectively studied the results of adenosine and dipyridamole perfusion imaging in a large group of patients who underwent pharmacologic stress radionuclide perfusion imaging. One thousand patients given dipyridamole between April ...
Nascimben L - - 1995
BACKGROUND: Converting enzyme inhibitor treatment of congestive heart failure slows progression to failure and reduces mortality rate. It is known whether these benefits are due solely to improved hemodynamics or also to improved myocyte energetics. This study examines the effect of enalapril treatment on both isovolumic contractile performance and its ...
Conti J B - - 1995
BACKGROUND: Adenosine administered intravenously terminates supraventricular tachycardias (SVT) involving the AV node as part of the reentrant circuit. Dipyridamole increases interstitial myocardial levels of this nucleoside. This study was designed to determine whether intravenous dipyridamole increases coronary sinus plasma adenosine concentrations ([Ado]cs) in humans to levels sufficient to alter electrophysiological ...
Jackson D C - - 1995
In vitro working hearts of the turtle, Chrysemys picta bellii, paced at 30 beats/min, were studied over a range of input pressures in the following sequence of perfusion conditions: control normoxia, control anoxia, lactacidotic normoxia, and lactacidotic anoxia. Two such series of experiments were performed. In series 1 (n = ...
Pagliaro P - - 1995
In 5 anaesthetized vagotomized dogs the administration of an inhibitor of the synthesis of nitric oxide (NO) was seen to reduce the heart rate, although the arterial pressure was prevented from increasing. Such a finding suggests that the inhibition of nitric oxide release can produce bradycardia without the involvement of ...
Cano C - - 1995
Adenosine produced a negative inotropic effect in hearts isolated from calm rabbits but not from those exhibiting alarm behavior during handling. This study was conducted to determine whether protein kinase C (PKC) activation is responsible for the loss of adenosine-induced negative inotropism in the hearts of hyperexcited rabbits. Adenosine (10 ...
Brurok H - - 1995
RATIONALE AND OBJECTIVES: Manganese dipyridoxyl diphosphate (MnDPDP) is a promising contrast agent for magnetic resonance imaging of the liver. The authors explored the possibility that high concentrations of MnDPDP may cause manganese ion (Mn++)-induced side effects on cardiac function. METHODS: Potential cardiodepression by MnDPDP, DPDP--, and manganese chloride (MnCl2) (100-3,000 ...
Wikström G - - 1995
A diagonal branch of the left anterior descending artery was occluded for 80 min. One microdialysis probe was inserted in the ischaemic area and two in the non-ischaemic areas. In six animals radiolabelled microspheres were injected before and during ischaemia and after reperfusion to monitor flow. Arterial and pulmonary artery ...
Itoh S - - 1995
1. The effects of OPC-18790, a novel positive inotropic agent, on cardiac function and myocardial energy metabolism in the guinea-pig isolated heart with ischaemia were studied by 31P-magnetic resonance spectroscopy (MRS) and compared with those of amrinone and dobutamine. 2. Cardiac ischaemia was induced by intracoronary infusion of 15 microns ...
Mathôt R A - - 1995
1. The aim of the present investigation was to determine the relationship between the blood concentration and haemodynamic effects of the adenosine A2a receptor agonist, CGS 21680C (the sodium salt of 2-p-(2-carboxyethyl)phenylethylamino-5'-N-ethylcarboxamidoadeno sin e) in conscious normotensive rats. 2. Chronically cannulated rats were randomly assigned to three groups which received ...
Rath D P - - 1995
BACKGROUND: Transmural analyses of the creatine phosphate (CP)/ATP ratio in various lamina of the canine myocardium have previously revealed significant variations in the CP/ATP ratio, with the subendocardial layer displaying a decreased ratio relative to the subepicardial layer. Without exception, these results were obtained under sodium pentobarbital anesthesia. These findings ...
Goossens A - - 1995
RATIONALE AND OBJECTIVES: Bolus injection of iodinated contrast media has been observed to alter myocardial mechanical function, but the consequences on cellular metabolism are poorly documented. Modifications of metabolic parameters (intracellular pH as well as adenosine triphosphate [ATP], phosphocreatine, and inorganic phosphate contents) and of mechanical function (coronary flow, heart ...
Houltz E - - 1995
The effects of adenosine on central hemodynamics, ST-segment changes, and left ventricular (LV) systolic and diastolic function, determined by transesophageal 2-D and Doppler echocardiography, were investigated in 20 patients shortly after coronary surgery. After control measurements, adenosine was infused at incremental infusion rates (30, 60, and 120 micrograms.kg-1.min-1). Adenosine caused ...
Pettersen M D - - 1995
We sought to determine the role of adenosine in the sustained but reversible decrease in cardiac neurotransmission that occurs after brief ischemia. Adult mongrel dogs were anesthetized and instrumented for measurements of heart rate, arterial pressure, and left anterior descending coronary artery (LAD) and left circumflex coronary artery (LCX) flow ...
Rath D P - - 1995
In this work, an x-irradiation/high fat/high cholesterol diet-induced atherogenic model was invoked to examine the effects of severe diffuse atherosclerosis on myocardial metabolism in the in vivo porcine heart. This model was studied using spatially localized 31P-nuclear magnetic resonance (NMR) to monitor pH and the levels of inorganic phosphate, phosphomonoesters, ...
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