Effect of papaverine on cyclic AMP, calcium uptake and force of contraction in isolated guinea-pig auricles.

The effects of papaverine on cyclic AMP (c-AMP), 45 calcium uptake and force of contraction were studied in electrically stimulated left guinea-pig auricles. Papaverine (2 x 10(-6) - 2 x 10(-5)M produced a concentration-dependent positive inotropic effect which was not affected by 10(-7) M propranolol. Papaverine (10(-5)M increased cyclic AMP; this effect developed faster than the increase in twitch tension. Papaverine (10(-5)M) enhanced 45calcium uptake. These results are taken to support the idea of a causative series of interactions between a papaverine induced increase in c-AMP, calcium uptake and force of contraction.