[Effect of cadmium on electromechanical coupling in the frog myocardium].

CdCl2 (0.2-0.5 mM) shortened the duration of action potential and reduced the tension of frog ventricular strips. CdCl2 completely blocked slow AP in partially depolarized strips and abolished both the tonic and phasic components of KCl-induced contractures. CdCl2 prevents adrenaline, NiCl2 and low-Na Ringer solution to produce tension potentiation. Cd seems to block the slow Na-Ca channels of frog myocardium and disturb intracellular Ca distribution by its ability to block protein SH-groups.