Caffeine, Calcium and the Activation of Contraction

Abstract

It has been known for some time that caffeine promotes activation and impedes inactivation of phasic muscle fibres. This occurs despite the fact that low concentrations of the drug have no effect on the electrical characteristics of the excitable membrane and on the actomyosin system of striated muscle fibres (Axelsson & Thesleff, 1958; Korey, 1950; Hasselbach, 1953). This leaves some part of the extensive tubular system as the most probable site of drug action (Sandow, 1965). The experiments with isolated muscle fibres described here provide some further information about the effect of caffeine on the coupling mechanism between excitation and contraction (Lüttgau & Oetliker, 1968). They also show how the drug—because of its specific action—can be useful in elucidating the causes of muscular failure (Lobsiger, 1968). References to further publications can be found in a review article by Sandow (1965).