Autoantibodies against ADP/ATP carrier from patients with dilated cardiomyopathy increase activity of voltage-dependent Ca channels in isolated cardiac myocytes.

The effects of autoantibodies against the ADP/ATP carrier, from sera of patients with dilated cardiomyopathy, on calcium channel current (ICa) were studied in enzymatically-isolated guinea pig ventricular myocytes by using a whole cell patch-clamp method. The results showed that the autoantibodies enhanced ICa in a concentration-dependent manner. Verapamil inhibited enhancement of ICa induced by the autoantibodies. Control sera (without the autoantibodies) did not affect ICa. This study suggests that anti-ADP/ATP carrier autoantibodies from sera of patients with dilated cardiomyopathy may enhance ICa and cause calcium overload. Disturbing Ca-channel gating by autoantibodies may contribute to the pathogenesis of dilated cardiomyopathy.