Both local anaesthetics and calcium antagonists depress cardiac function. Therefore, we have studied the interaction of these compounds in the isolated myocardium of guineapigs. The negative inotropic effect of various local anaesthetics was investigated in left atria in the absence or presence of nitrendipine 10(-7) mol litre-1 (n = 7-8 in each group). In addition, the effect of bupivacaine wa...

The inotropic agent in the context of heart failure and angina is classified into positive and negative inotropic agent. The positive agent increases the contractility and will be discussed in detail in this article. A brief about the negative inotropic agent, which decreases the myocardial contractility, is mentioned. The inotropic agent, when mentioned alone without any prefix, stands for a p...

The cardiovascular effects of a single dose of two short-acting intravenous anaesthetics, methohexitone and propanidid, were studied in ten healthy male volunteers. The doses used were selected to produce clinical anaesthesia of similar depth and duration. Methohexitone increased heart rate initially without changing arterial or filling pressures. The C(a-v)02 difference was decreased, suggesti...

To investigate the effects of verapamil on left ventricular systolic and diastolic function in patients with hypertrophic cardiomyopathy, we studied 14 patients at catheterization with a nonimaging scintillation probe before and after serial intravenous infusions of low-, medium-, and high-dose verapamil (total dose 0.17 to 0.72 mg/kg). Percent change in radionuclide stroke counts after verapam...

To study the inotropic effect of enhanced Na(+)-Ca(2+) exchange in the rat papillary muscles and isolated heart, the developed tension in the rat papillary muscles was measured and the left ventricular functions were assessed in the isolated rat heart. E-4031, a selective activator for Na(+)-Ca(2+) exchange in rats, concentration-dependently increased the developed contractile tension in the ra...

The effects of insulin (In) on contractile activity of isolated cardiac muscle were studied in right ventricular moderator band (MB) of piglets and papillary muscle (PM) of cats and kittens. The muscles were bathed in modified Krebs solution containing 5.6 mM glucose at 30 degrees C and gassed with 95% O2 and 5% CO2. They were paced at 24 contractions per minute isometrically at Lmax. Addition ...

BACKGROUND Apelin, the endogenous ligand for the G protein-coupled apelin receptor, is an important regulator of the cardiovascular homoeostasis. We previously demonstrated that apelin is one of the most potent endogenous stimulators of cardiac contractility; however, its underlying signaling mechanisms remain largely elusive. In this study we characterized the contribution of protein kinase C ...

Propofol is a widely used intravenous general anesthetic. The negative inotropic effect of propofol has been best explained by inhibition of the L-type Ca(2+) current (I(Ca)). Using guinea-pig cardiac preparations, however, we found that the propofol concentration producing a 50% decrease in force of contraction was more than 10 times higher than that producing a 50% inhibition of I(Ca), implyi...

The right atrium isolated from the dog heart was perfused through the cannulated sinus node artery with heparinized arterial blood led from a support dog anesthesized with 30 mg/Kg of sodium pentobarbital. When adenosine was administered into the sinus node artery, negative chronotropic and inotropic effects were dose-relatedly induced. The threshold dose for inducing the negative ones was 0.3 ...

The time course of the effects of phenylephrine (10 mumol/l) on force of contraction and on inositol phosphates in electrically driven left auricles from rat hearts labeled with [3H]inositol was studied. All experiments were performed in the presence of propranolol (1 mumol/l) and LiCl (10 mmol/l). Products measured after separation with high-performance liquid chromatography were inositol 1-ph...