Comparison of verapamil and bepridil in the therapy of familiar cardiomyopathy of the Syrian hamster.

The effect of bepridil compared to verapamil on the cardiomyopathic hamster (Strain Bio 8262) was evaluated. Bepridil (10 mg/kg) was injected twice daily for 15 and 30 days. Verapamil (10 mg/kg) was injected twice daily for 30 days. Control animals were treated with NaCl. After life-day 30, large infarct-like lesions predominantly located in the central portion of the left ventricular walls were observed, while single cell necrosis occurred only in a few cases. In peripheral muscles, the necrotizing process started even before life-day 30. In the skeletal muscles, small foci of cell necrosis were the predominant type of lesion. Myocardial calcium accumulation and cell necrosis could be completely prevented by verapamil and were not influenced by bepridil. Both drugs were ineffective in the skeletal muscles. The infarct-like lesions of the myocardium demonstrate that a vascular component is involved in the pathogenesis of necrosis, in addition to the inherited disturbance of calcium metabolism. The results demonstrate that not all drugs with calcium antagonistic potencies have identical cardioprotective effects in the cardiomyopathic hamster.