Effect of caffeine on cardiac contractile activity and radiocalcium movement

Abstract

Caffeine induced a positive inotropic response in toad ventricular muscle. The magnitude of the inotropic response was influenced by the concentration of Na+ and Ca++ in the perfusate and by the rate of stimulation. Caffeine abolished poststimulation potentiation and the "staircase" phenomenon, and evoked an increase in the inward and outward movement of Ca45. The positive inotropic activity of caffeine can be related to the changed movement of Ca++.