Bay k 8644 is a structural analog of nifedipine with positive inotropic activity. The mechanism of drug action was evaluated by measuring the effects of Bay k 8644 on twitch tension, action potential configuration, and calcium channel currents in myocardial cells. Bay k 8644 increases twitch tension in guinea pig atria without changing the time course of tension development. The drug does not o...

THE effects of halogenated anesthetics on the myocardium have been studied extensively in vivo and in vitro in various animal species. In the past, investigators have focused their efforts on heart function, myocardial mechanics, and electrophysiology. During recent years, considerable knowledge has been obtained by new investigative methodologies, including molecular and cellular biology and a...

Background. Although a-adrenergic receptors are present in both normal and failing human left ventricular myocardium and mediate a positive inotropic effect in several other species, it is not known whether stimulation of myocardial ca-adrenergic receptors exerts a positive inotropic effect or contributes to basal contractile state in vivo in humans. Methods and Results. We studied 15 patients ...

Application of electrical field to the heart during the refractory period of the beat has been shown to increase the force of contraction both in animal models and in heart failure patients (cardiac contractility modulation, or CCM). A direct increase in intracellular calcium during CCM has been suggested to be the mechanism behind the positive inotropic effect of CCM. We studied the effect of ...

objective: in ventricular arrhythmias, due to their free radical scavenging action, antioxidant agents are usually used in the treatment of cardiovascular disease. since stress is considered as risk factor for increased mortality by causing malignant arrhythmias, the study was designed to evaluate the cardioprotective effects of ellagic acid (ea) on cacl2-induced arrhythmias in rat stress model...

A mrinone has been a great forerunner of noncatechol and nonglycoside novel cardiotonic agents and given an extraordinary strong impact in the development of novel cardiotonic agents. Unexpectedly, amrinone failed to rescue the patients with chronic heart failure, thereby produced a prominent paradigm shift from inotropic to cardioprotective therapy, and contributed to advances in the current p...

The aim of this study was to investigate whether the positive inotropic effects of the beta 2-adrenoceptor agonist salbutamol are increased by foreshortening of the diaphragm, and to determine the mechanism of action of these effects. Diaphragm strips were studied either at optimal resting length (Lo) or at approximately 70% Lo. In an initial experiment (Experiment I) salbutamol was added to th...

Clenbuterol, a compound classified as a beta2-adrenoceptor (AR) agonist, has been employed in combination with left ventricular assist devices (LVADs) to treat patients with severe heart failure. Previous studies have shown that chronic administration of clenbuterol affects cardiac excitation-contraction coupling. However, the acute effects of clenbuterol and the signaling pathway involved rema...

Cultured monolayers of spontaneously contracting chick embryo ventricular cells were perfused with culture medium containing ouabain. Contractile state was monitored by an optical-video system recording amplitude and velocity of cell wall motion. Positive inotropic effects of 2.5 x 10(-7) to 10(-6) M ouabain were manifest within 1.5-2 min, and reached a stable plateau within 5-6 min. The inotro...

The effects of intravenous administration of sodium nitroprusside to a donor dog on cardiac pacemaker activity and contractility were investigated in a cross-circulated dog heart preparation; i.e., the isolated atrial muscle was perfused with blood from a pentobarbital anesthetized donor dog. Intravenous administration of nitroprusside (1-10 micrograms/Kg) caused a hypotension with tachycardia,...