• The purpose of this paper is to identify the active molecular species of a drug, theophylline, which exists simultaneously in the ionized and nonionized states at pH 7.4. Previous studies by Hardman et al. and Baird and Hardman have related changes in cardiac function to the concentration of nonionized or ionized drugs in the extracellular fluid perfusing isolated hearts. Such correlations do...

1. To date no study has described the cardiovascular effects of increased myofilament Ca2+ responsiveness in awake animals both under resting conditions and during treadmill exercise. In the present study we therefore investigated the systemic, pulmonary and coronary haemodynamic actions of the Ca2+ sensitizer EMD 57033 in 16 chronically instrumented awake pigs at rest and during treadmill exer...

A phosphodiesterase (PDE) III inhibitor, amrinone, inhibited both the negative inotropic actions of verapamil and nicardipine in guinea pig ventricular papillary muscle; this effect was canceled by the protein kinase A inhibitor H-89. The PDE IV inhibitor 1,3-di-n-butyl-7-(2'-oxopropyl)xanthine (denbufylline), which elicited a negative inotropic action by itself, attenuated the action of verapa...

The effects of potassium chloride on inotropic and chronotropic activity were investigated in five isolated canine atrium preparations which were suspended in a bath and perfused with arterial blood from the carotid artery of the heparinized support dog. Potassium chloride administered into the cannulated sinus node artery in a dose range of 100 mug-1 mg produced a dose-related negative inotrop...

BACKGROUND Conflicting opinions are present in the literature regarding the origin of the negative inotropic effect of propofol on the myocardium. This study aims to resolve these discrepancies by investigating the inotropic effects of propofol the L-type calcium channels and the sodium-calcium exchanger (NCX). METHODS The effect of 20 microg/ml propofol on force development was determined in...

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...

Atria from mice fed a selenium-deficient (Se(-)) diet have a diminished beta-adrenoceptor-inotropic cardiac response to isoproterenol or norepinephrine compared with atria from mice fed the same diet supplemented with 0.2 mg/kg Se as sodium selenite (Se(+)). This diminished response could be reversed by feeding Se(-) mice the Se(+) diet for 1 wk or by pretreatment with nitric oxide synthase (NO...

myocardial dysfunction is a major complication in cardiac surgery that needs inotropic support. this study evaluates the effect of milrinone on patients with low ventricular ejection fraction undergoing off- pump coronary artery bypass graft (opcab). the present study is designed to evaluate the effect of milrinone on myocardial dysfunction. eighty patients with low ventricular ejection fractio...

OBJECTIVE Xanthine oxidase (XO) inhibitors enhance myofilament Ca(2+) responsiveness of normal rat myocardium. We examined whether this inotropic action is preserved or magnified in failing rat myocardium and whether the magnitude of this effect correlates with tissue xanthine-oxidoreductase (XOR) activity. METHODS Hearts of 18-20 month-old SHHF (spontaneous hypertensive/heart failure) rats w...

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...