We have shown reduced density and altered kinetics in slowly activating K+ currents (I(Ks)) in epicardial border zone (EBZ) cells (IZs) of the 5-day-infarcted canine heart (Jiang M, Cabo, C, Yao J-A, Boyden PA, and Tseng G-N. Cardiovasc Res 48: 34-43, 2000). beta-Adrenergic stimulation with isoproterenol increases I(Ks) in normal cells (NZs). In this study, we used a voltage-clamp protocol with...

The aim of the present study was to evaluate the effect of overstimulation of beta-adrenoceptors on vascular inflammatory mediators. Wistar rats were treated with the beta-adrenoceptor agonist isoproterenol (0.3 mg.kg(-1).day(-1) sc) or vehicle (control) for 7 days. At the end of treatment, the right carotid artery was catheterized for arterial and left ventricular (LV) hemodynamic evaluation. ...

Males exhibit enhanced myocardial ischemia-reperfusion injury versus females under hypercontractile conditions associated with increased sarcoplasmic reticulum (SR) Ca2+. We therefore examined whether there were gender differences in SR Ca2+. We used NMR Ca2+ indicator 1,2-bis(2-amino-5,6-difluorophenoxy)-ethane-N,N,N',N'-tetraacetic acid to measure SR Ca2+ in perfused rabbit hearts. Isoprotere...

We have used wild type 549 lymphoma cells and S49 variants that have lesions in their ability to generate CAMP to explore the mechanism of activation of adenylate cyclase by the diterpene forskolin. In intact wild type cells, forskolin rapidly and reversibly stimulated CAMP accumulation several hundred-fold over basal levels. Simultaneous addition of forskolin and the padrenergic agonist isopro...

OBJECTIVES The purpose of this study was to investigate and compare the effects of the beta-adrenergic agonist, isoproterenol, on induced increase in melatonin production in the pineal gland of young and old rats, at different circadian stages. MATERIALS AND METHODS We report here the effects of 10(-6) M isoproterenol-stimulated melatonin production by perifused pineal glands obtained from yo...

BACKGROUND Prior research has suggested a weaker parasympathetic antagonism of sympathetic effects on the heart in type A (coronary-prone) men. To confirm this phenomenon and extend our understanding of it, we investigated the effects of prior muscarinic blockade on the electrocardiogram T wave and other cardiovascular and neuroendocrine responses to isoproterenol in type A and type B (non-coro...

To determine the effect of isoproterenol on cardiac energetics and function in an animal preparation of cardiomyopathy, we studied Langendorff perfused hearts from Syrian cardiomyopathic hamsters. High-energy phosphate metabolites (phosphocreatine [PCr], ATP, inorganic phosphate [Pi]) and intracellular pH (pHi) were measured by 31P nuclear magnetic resonance spectroscopy and correlated with lef...

Several cytochrome P450 (P450) enzymes have been identified in the heart, and their levels have been reported to be altered during cardiac hypertrophy. Moreover, there is a strong correlation between P450-mediated arachidonic acid metabolites and the pathogenesis of cardiac hypertrophy. Therefore, we investigated the effect of isoproterenol-induced cardiac hypertrophy on the expression of sever...

The ability of catecholamines and glucagon to stimulate glycogen phosphorylase activity was examined in hepatocytes isolated from euthyroid and hypothyroid fed female rats. Hypothyroidism did not alter the ability of either phenylephrine or epinephrine to activate glycogen phosphorylase. Activation of glycogen phosphorylase in response to a maximal concentration of isoproterenol, however, was 1...

These experiments examined water-drinking and arterial blood pressure responses to β-adrenergic receptor activation in young (4 mo), "middle-aged" adult (12 mo), and old (29 mo) male rats of the Brown-Norway strain. We used isoproterenol to simultaneously activate β(1)- and β(2)-adrenergic receptors, salbutamol to selectively activate β(2)-adrenergic receptors, and the combination of isoprotere...