The effect of procainamide and digoxin, singly and together, on peak active force and rate of force development of isolated right ventricular papillary muscles from adult cats was examined. Procainamide (1.5 X 10(-5) M) increased force and rate of force development in each muscle with further increments in performance up to 2.4 X 10(-4) M in most muscles. The maximal increases in force (+/- SEM...

The positive inotropic action of blood plasma on isolated hearts has been known for a long time (Bowditch, 1871; Ringer, 1885; Clark, 1913; Hajdu, 1957; Hajdu, Leonard & Akers, 1957a; Hajdu, Weiss & Titus, 1957 b), and the observations recorded by various authors suggest that a number of different plasma components are responsible for positive inotropic activity. Hajdu et al. (1957b) isolated a...

BACKGROUND AND PURPOSE Despite the view that only β2- as opposed to β1-adrenoceptors (βARs) couple to G(i), some data indicate that the β1AR-evoked inotropic response is also influenced by the inhibition of Gi. Therefore, we wanted to determine if Gi exerts tonic receptor-independent inhibition upon basal adenylyl cyclase (AC) activity in cardiomyocytes. EXPERIMENTAL APPROACH We used the Gs-s...

Glucagon increased heart rate and contractile force in the anesthetized dog and increased isometric tension in the isolated dog papillary muscle. The positive inotropic and chronotropic responses were not abolished or reduced by previous administration of the beta-receptor blocking agent propranolol, in doses of 0.5 mg/kg. Glucagon increased the force and rate of cardiac contraction even when c...

Classic inotropic agents provide short-term haemodynamic improvement in patients with heart failure, but their use has been associated with poor prognosis. A new category of inotropic agents, the Ca(2+) sensitizers, may provide an alternative longer lasting solution. Levosimendan is a relatively new Ca(2+) sensitizer which offers haemodynamic and symptomatic improvement by combining a positive ...

Adrenomedullin (ADM) is an endogenous peptide with favorable hemodynamic effects in vivo. In this study, we characterized the direct functional effects of ADM in isolated preparations from human atria and ventricles. In electrically stimulated human nonfailing right atrial trabeculae, ADM (0.0001-1 micromol/l) increased force of contraction in a concentration-dependent manner, with a maximal in...

Objectives: Anti ischemic reperfusion effect of crude methanol extract of Desmodium gangeticum root had been reported earlier but how is modulating its cardiotonic effect to render cardio-protection is largely unknown. Methods: The inotropic effect of methanol extract of Desmodium gangeticum root was investigated on isolated frog heart and further analyzed the physiological and biochemical effe...