Thrombin stimulates Ca-channel currents in isolated frog ventricular cells

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Abstract
Effects of the proteolytic enzyme thrombin in the modulation of cardiac Ca-channel currents were examined in single ventricular cells from frog myocardium, using the whole-cell voltage clamp technique (Hamill et al. 1981). Application of 3.8·10−9 M thrombin to the bath increased the peak of the Ca-channel current by 84±35% (8 cells). Hirudin (31·10−9 M), a specific thrombin inhibitor, blocked the thrombin-induced increase of this current. The increase in the current can be made responsible for the measured positive inotropic effects of thrombin as well as for the shift of the plateau voltage of the action potentials towards more positive values.