Search Results
Results 201 - 250 of 882
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Stecyk Jonathan A W - - 2007
Despite adenosine being regarded as an important signaling molecule capable of coordinating ATP supply and demand during periods of oxygen deprivation in anoxia-intolerant mammals, the importance of adenosinergic cardiovascular control in anoxia-tolerant vertebrates is poorly understood. Here, we report on adenosinergic cardiovascular control during normoxia and prolonged (hours to days) ...
Farrell A P - - 2007
Most vertebrates die within minutes when deprived of molecular oxygen (anoxia), in part because of cardiac failure, which can be traced to an inadequate matching of cardiac ATP supply to ATP demand. Cardiac power output (PO; estimated from the product of cardiac output and central arterial pressure and an indirect ...
Lewandowski E Douglas ED Program in Integrative Cardiac Metabolism, 835 S. Wolcott Ave., MC901, University of Illinois, College of Medicine, Chicago, IL 60612, USA. - - 2007
Glucose metabolism in the heart requires oxidation of cytosolic NADH from glycolysis. This study examines shuttling reducing equivalents from the cytosol to the mitochondria via the activity and expression of the oxoglutarate-malate carrier (OMC) in rat hearts subjected to 2 wk (Hyp2, n = 6) and 10 wk (Hyp10, n ...
Lehtonen Lasse - - 2007
Calcium sensitizers are a new group of inotropic drugs. Levosimendan is the only calcium sensitizer in clinical use in Europe. Its mechanism of action includes both calcium sensitization of contractile proteins and the opening of adenosine triphosphate (ATP)-dependent potassium channels as mechanism of vasodilation. The combination of K-channel opening with ...
Lange Matthias - - 2006
In severe sepsis and septic shock, hemodynamic support is often complicated by a tachyphylaxis against exogenous catecholamines. Because activation of adenosine triphosphate (ATP)-sensitive potassium (K(ATP)) channels plays a pivotal role in the pathogenesis of hyperdynamic vasodilatory shock, we hypothesized that it may be beneficial to administer a specific K(ATP) channel ...
Willems Laura - - 2007
There is mixed evidence adenosine receptors (ARs) may enhance myocardial contractility, although this remains contentious. We assessed inotropic actions of adenosine (50 muM) and selective AR activation with 100 nM N (6)-cyclohexyladenosine (CHA; A(1)AR agonist), 25 nM 2-[p-(2-carboxyethyl) phenethylamino]-5'-N-ethylcarboxamidoadenosine (CGS-21680; A(2A)AR agonist) and 100 nM 2-chloro-N (6)-(3-iodobenzyl)-adenosine-5'-N-methyluronamide (Cl-IB-MECA; A(3)AR agonist) ...
Friedman Seth D - - 2007
Substantial controversy persists in the literature concerning the physiologic consequences hypocapnia, or low partial pressure of carbon dioxide (PaCO(2)). Invasive animal studies have demonstrated large pH increases (>0.25 U), phosphocreatine (PCr) decreases (>30%), and adenosine triphosphate (ATP) decreases (>10%) after hyperventilation (HV) (20 mm Hg PaCO(2)). However, using magnetic resonance ...
Conil Nathalie - - 2006
We present isotropic, elastic-plastic finite element calculations detailing the pressure relationship between an inclusion and its surrounding matrix, subject to an externally imposed hydrostatic strain. In general, the inclusion and the matrix have different values of hydrostatic pressure, depending on their absolute and relative values of Young's modulus and Poisson's ...
Mao Ho-Kwang - - 2006
The elasticity and plasticity of materials at high pressure are of great importance for the fundamental insight they provide on bonding properties in dense matter and for applications ranging from geophysics to materials technology. We studied pressure-solidified argon with a boron-epoxy-beryllium composite gasket in a diamond anvil cell (DAC). Employing ...
Wang Lixing - - 2006
BACKGROUND: Mitochondrial dysfunction may contribute to early postoperative neonatal heart dysfunction. Diazoxide, a mitochondrial-selective adenosine triphosphate-sensitive potassium-channel opener, is associated with mitochondrial preservation after cardioplegic arrest. We evaluated the mitochondrial-protective effect of diazoxide in terms of mitochondrial structure and function after neonatal cardioplegic arrest. METHODS: Newborn piglets (age, approximately 14 ...
Willems Laura - - 2006
OBJECTIVE: Adenosine deaminase (ADA) may be multifunctional, regulating adenosine levels and adenosine receptor (AR) agonism, and potentially modifying AR functionality. Herein we assess effects of ADA (and A1AR) deficiency on AR-mediated responses and ischaemic tolerance. METHODS: Normoxic function and responses to 20 or 25 min ischaemia and 45 min reperfusion ...
Imai E - - 2006
Intradialytic hypotension is a most frequent complication of hemodialysis and may contribute to cardiovascular events and high mortality. There is a hypothesis that an increase in adenosine generation during hemodialysis may cause vasodilation and a decrease in cardiac output, which results in systemic hypotension. We studied whether this can be ...
Lynch Fiona M - - 2006
1. The ATP-sensitive potassium (K(ATP)) channel may be an important mediator of metabolic dilation in the human coronary circulation. As adenosine and hypoxia are considered to be major mediators of metabolic dilation in the coronary circulation, we investigated the effect of glibenclamide (a K(ATP) channel blocker) on adenosine and hypoxic ...
Paolocci Nazareno - - 2006
Cardiac matrix metalloproteinases (MMPs) stimulated by the sympathomimetic action of angiotensin II (AII) exacerbate chamber diastolic stiffening in models of subacute heart failure. Here we tested the hypothesis that MMP inhibition prevents such stiffening by favorably modulating high-energy phosphate (HEP) stores more than by effects on matrix remodeling. Dogs were ...
Ueda Takashi - - 2006
Olprinone, a phosphodiesterase (PDE) 3 inhibitor, is used to treat heart failure due to its positive inotropic and vasodilative effects. Selective inhibition of the PDE 3 isozyme increases intracellular adenosine 3;5;-cyclic monophosphate and enhances Ca(2+) influx into cardiac muscle cells. The most significant advantage of PDE 3 inhibitors is their ...
Viant Mark R - - 2006
Changes in metabolism of Japanese medaka (Oryzias latipes) embryos exposed to dinoseb (2-sec-butyl-4,6-dinitrophenol), a substituted dinitrophenol herbicide, were determined by in vivo (31)P NMR, high-pressure liquid chromatography (HPLC)-UV, and (1)H NMR metabolomics. ATP and phosphocreatine (PCr) metabolism were characterized within intact embryos by in vivo (31)P NMR; concentrations of ATP, ...
Rodriguez-Porcel Martin M Department of Internal Medicine, Division of Cardiovascular Disease, Mayo Clinic College of Medicine, 200 First St. SW, Rochester, Minnesota 55905, - - 2006
Advanced hypertension (HT), associated with left ventricular hypertrophy (LVH), impairs myocardial microvascular function and structure and leads to increased myocardial hypoxia and growth factor activation. However, the effect of HT on microvascular architecture and its relation to microvascular function, before the development of LVH (early HT), remains unclear. By way ...
Gilani Anwar H - - 2005
Crude extract of Valeriana wallichii rhizome (Vw.Cr) and its fractions were studied for possible antispasmodic and blood pressure lowering activities to rationalize some of the folkloric uses. In rabbit jejunum preparations, Vw.Cr (0.1-3.0 mg/mL) caused relaxation of spontaneous contractions. When tested against high K(+) (80 mM)-induced contractions it produced weak ...
Peltier S - - 2005
We studied the effect of exogenous adenosine in isolated perfused normoxic rat hearts on glycolytic flux through pyruvate kinase (PK). We compared its effect with that of myxothiazol, an inhibitor of mitochondrial ATP production. Moreover, we tested whether an increase of membrane ionic flux with monensin is linked to a ...
Wierema Thomas K A - - 2005
BACKGROUND: Adenosine is an endogenous nucleoside with potent vasodilatory capacities, released under ischaemic conditions in particular. Its mechanisms of action, however, remain elusive. OBJECTIVE: To evaluate the role of adenosine, using a non-selective purinergic receptor antagonist, and the possible involvement of nitric oxide in this mechanism. In addition, the production ...
Shen Weiqun - - 2005
Decreases in total creatine kinase (CK) activity and creatine [Cr] combine to limit the capacity of the failing heart to rapidly re-synthesize ATP (energy reserve). If the loss in energy reserve could be reversed, cardiac contractile reserve may be improved. Here we test whether these changes are reversible during recovery ...
Kisch-Wedel Hille - - 2005
The prostaglandin I2 analogues epoprostenol and iloprost increase left ventricular contractility. Therefore, we hypothesize that the prostaglandin I2 analogues epoprostenol and iloprost improve also left ventricular diastolic function. To test this hypothesis, the effects of epoprostenol and iloprost on left ventricular diastolic function were assessed in vivo and compared to ...
Yao Song T - - 2005
1 The purpose of the present study was to determine whether purines exerted a physiological role in central cardiovascular modulation at the level of the locus coeruleus (LC). 2 In pentobarbitone-anaesthetised Wistar-Kyoto rats, unilateral microinjection of ATP or alpha,beta-methyleneATP into the LC elicited dose-related decreases in blood pressure and heart ...
Mishra Rakesh K - - 2005
OBJECTIVES: The goal of this study was to determine the relationship between changes in cardiac hemodynamics during intravenous adenosine (ADO) infusion, and myocardial blood flow (MBF). BACKGROUND: The relationship between changes in MBF and the peripheral hemodynamic effects during peak adenosine infusion is unknown. METHODS: We studied 348 (age 57 ...
Reichelt Melissa E - - 2005
Adenosine receptors may be important determinants of intrinsic ischemic tolerance. Genetically modified mice were used to examine effects of global A1 adenosine receptor (A1AR) knockout (KO) on function and ischemic tolerance in perfused mouse hearts. Baseline contractile function and heart rate were unaltered by A1AR KO, which was shown to ...
Marin Rodrigo M - - 2005
In isolated rat hearts perfused with HEPES and red blood cell-enriched buffers, we examined changes in left ventricular pressure induced by increases in heart rate or infusion of adenosine to investigate whether the negative force-frequency relation and the positive inotropic effect of adenosine are related to an inadequate oxygen supply ...
Schaddelee Marloes P - - 2004
The objective of this investigation was to characterise the pharmacokinetic-pharmacodynamic correlation of 5'-deoxy-N6-cyclopentyl-adenosine (5'dCPA) in the chronic constriction injury model of neuropathic pain. Following intravenous administration of 5'dCPA (0.30 or 0.75 mg kg(-1)), the time course of the drug concentration in plasma was determined in conjunction with the effect on ...
Burki Nausherwan K - - 2005
Intravenous adenosine for the treatment of supraventricular tachycardia is reported to cause bronchospasm and dyspnea and to increase ventilation in humans, but these effects have not been systematically studied. We therefore compared the effects of 10 mg of intravenous adenosine with placebo in 21 normal subjects under normoxic conditions and ...
Wyon Matthew A - - 2004
The aim of the present study was to examine whether the workload, expressed in oxygen uptake and heart rate, during dance class and rehearsal prepared the dancer for performance. Previous research on the demands of class and performance has been affected by equipment limitations and could only provide limited insight ...
Shen Fu-Ming - - 2004
With a computerized analysis system, blood pressure was recorded continuously in conscious unrestrained spontaneously hypertensive rats. The effects of different adenosine receptor agonists and ATP-sensitive potassium channel opener and blocker on blood pressure variability in spontaneously hypertensive rats were studied. It was found that adenosine, 5'-N-cyclopropyl-carboxamidoadenosine (CPCA, a selective adenosine ...
Ziyatdinova N I - - 2004
The effects of electrical stimulation of the vagus nerve on the negative chronotropic and hypotensive effects of adenosine were studied on adult rats. Intravenous injection of adenosine to control rats significantly reduced the heart rate and induced a transient blood pressure drop followed its increase. Preliminary electrical stimulation of the ...
Konno Takashi - - 2004
We evaluated the activities of 2-alkynyladenosine derivatives, relatively selective adenosine A2 receptor agonists, in the intraocular pressure regulation in rabbits. An adenosine A2 receptor agonist 2-[p-(2-carboxyethyl)phenylethylamino]-5'-N-ethylcarboxamidoadenosine (CGS-21680) decreased intraocular pressure, while another A2 receptor agonist 2-(phenylamino)adenosine transiently increased it. The first group of 2-alkynyladenosine derivatives (1-hexyn-1-yl derivatives) caused a transient ...
Ng Cho - - 2004
OBJECTIVE: To determine the effect of adenosine for the management of persistent pulmonary hypertension of the newborn. DESIGN: Prospective, observational case series report. SETTING: A single, tertiary referral neonatal intensive care unit. PATIENTS: Nine neonates with persistent pulmonary hypertension of the newborn requiring mechanical ventilation and inhaled nitric oxide at ...
Timmers Henri J L M - - 2004
The direct vasodilatory and negative chronotropic effects of adenosine in humans are counterbalanced by a reflex increase in sympathetic nerve traffic. A suggested mechanism for this reflex includes peripheral chemoreceptor activation. We, therefore, assessed the contribution of carotid chemoreceptors to sympatho-excitation by adenosine. Muscle sympathetic nerve activity was recorded during ...
Kisch-Wedel Hille - - 2003
OBJECTIVE: The principal effects of prostaglandin I(2) are vasodilation and inhibition of platelet aggregation induced by a rise in the intracellular second messenger cAMP. In the heart a rise in intracellular myocardial cAMP increases contractility. We examined whether prostaglandin I(2) increases left ventricular contractility in vivo. The effects of epoprostenol ...
Leesar Massoud A - - 2003
OBJECTIVES: The objective of this study was to use electrocardiogram (ECG)-independent parameters to determine whether preconditioning (PC) exists in humans during percutaneous transluminal coronary angioplasty (PTCA). BACKGROUND: Several studies suggest that both ischemia and adenosine induce PC in the human heart during PTCA. However, because almost all of these studies ...
Leong H S - - 2003
Cardiac hypertrophy, induced by chronic pressure or volume overload, is associated with abnormalities in energy metabolism as well as characteristic increases in muscle mass and alterations in the structure of the heart. Hypertrophied hearts display increased rates of glycolysis and overall glucose utilization, but rates of pyruvate oxidation do not ...
Bin Jian-Ping - - 2003
The direct effects of dobutamine on capillary blood volume (VOL) and blood flow velocity (VEL) are not known. We hypothesized that these would be more similar to that of adenosine because of its effects on the beta(2) receptors on the coronary circulation. A total of 9 open-chest anesthetized dogs were ...
Hoffman William E - - 2003
OBJECTIVE: To compare adenosine-, isoflurane-, or desflurane-induced hypotension with and without left anterior descending (LAD) coronary artery constriction for the effects on myocardial tissue oxygen pressure (PmO(2)) in dogs. DESIGN: Prospective, randomized, nonblinded. SETTING: University teaching hospital. PARTICIPANTS: Male nonpurpose-bred dogs (n = 18). INTERVENTIONS: Dogs were anesthetized with 1.5% ...
Rich Preston B - - 2003
BACKGROUND: Extracellular nucleotides mediate many cellular functions and are released in response to mechanical stress in vitro. It is unknown whether adenosine triphosphate (ATP) is released in vivo during mechanical ventilation (MV). We hypothesized that stress from high-pressure MV would increase airway ATP, contributing to MV-associated lung edema. METHODS: Rats ...
Dobson Geoffrey P - - 2003
1. From the smallest shrew or bumble-bee bat to the largest blue whale, heart size varies by over seven orders of magnitude (from 12 mg to 600 kg). This study reviews the scaling relationships between heart design, cellular bioenergetics and mitochondrial efficiencies in mammals of different body sizes. 2. The ...
Mielke Marilyn M Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, - - 2003
Activation of the Na(+)/H(+) exchanger may play an important role in the development of cardiac hypertrophy. Isolated ventricular myocyte studies have suggested that angiotensin II (AII) has direct positive inotropic effect caused by intracellular alkalinization due to increased Na(+)/H(+) exchange, but whether this occurs in the whole heart is unknown. ...
Hua Dongping - - 2003
BACKGROUND: In this study, we evaluated the effects of fructose-1,6-diphosphate (FDP) on high-energy phosphate metabolism during 18-hour hypothermic rabbit-heart preservation. METHODS: Under general anesthesia and artificial ventilation, hearts from 42 adult New Zealand white rabbits were harvested, flushed, and preserved in St. Thomas solution at 4(o)C for 18 hours. In ...
Follath Ferenc - - 2003
The novel calcium sensitizer levosimendan improves myocardial contractility without causing an increase in intracellular calcium and cyclic adenosine monophosphate concentrations. It also has a vasodilator action due to an opening of the adenosine triphosphate-sensitive potassium channels. In a double-blind clinical trial levosimendan was compared with dobutamine in 203 patients with ...
Tawakol Ahmed - - 2003
OBJECTIVE: This study tests the hypothesis that elevated levels of rest myocardial blood flow (MBF), indicative of inefficient aerobic metabolism, will be present in some patients with mitochondrial disorders but structurally normal hearts. BACKGROUND: Regulation of MBF is a complex process closely linked to myocardial energy production. Aerobic metabolism in ...
McConville Patrick - - 2003
BACKGROUND: In the heart, striking functional differences exist after stimulation of the beta1- and beta2-adrenergic receptor (AR) subtypes. These may be linked to differences in metabolic response during beta1- and beta2-AR stimulation. METHODS AND RESULTS: The relation between work and metabolism was examined during selective beta1- and beta2-AR stimulation (beta1 ...
Kojic Zvezdana Z - - 2003
To test whether endothelium-derived nitric oxide (NO) regulates mitochondrial respiration, NO was pharmacologically modulated in isolated mouse hearts, which were perfused at constant flow to sensitively detect small changes in myocardial O2 consumption (MVO2). Stimulation of NO formation by 10 microM bradykinin (BK) increased coronary venous nitrite release fivefold to ...
Rose'Meyer Roselyn B - - 2003
In this study, we investigated the effect of noradrenaline depletion on contractile recovery in rat isolated heart following myocardial ischaemia. Groups tested included control tissues and hearts from reserpinised rats. Reserpine 1 mg/kg s.c. was injected into rats 18 to 24 h prior to experiments. Hearts underwent 15 min global ...
Hoffman W E - - 2003
BACKGROUND: Reports show that glyburide, an adenosine triphosphate sensitive potassium (K+ATP) channel blocker, will reverse the myocardial protective effect of inhalational anesthesia. We evaluated the effect of glyburide on myocardial tissue oxygen pressure (PmO2) in dogs anesthetized with desflurane. METHODS: Twelve dogs were anesthetized with 8% end-tidal desflurane for baseline ...
Agnihotri Arvind K - - 2003
BACKGROUND: Micropump additive systems allow for continuous modification of cardioplegia composition during heart surgery. Although the use of such systems in warm heart surgery is theoretically desirable, the role of the systems has been clinically limited by coronary vasoreactivity with higher potassium concentration and unreliable mechanical arrest at lower potassium ...
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