RESUMEN
Protein kinase C in vesicular preparations of the myocardium sarcolemma is shown to phosphorylate proteins with the molecular weight of 250, 140, 67, 58, 24 and 11 kD. The exogenic protein kinase C catalyzed phosphorylation of the sarcolemma preparations lowers the initial rate of the passive calcium transport from 0.56 down to 0.18 mmol per 1 mg second. Activation of endogenic protein kinase C by 4 beta-phorbol-12 beta-myristate-13 alpha-acetate is also accompanied by phosphorylation of vesicular preparations of sarcolemma and by inhibition of the passive calcium transport. Polymyxin B, being an inhibitor of protein kinase C, suppresses the phosphorylation and thus prevents the inhibitory action of phosphorylation on the passive calcium transport.