Dihydropyridine-induced release of catecholamines in cardiac tissue.

The symmetrically substituted dihydropyridine-dicarboxylate 3 exerts only weak calcium antagonistic activity on smooth muscles compared with the standard nifedipine. On electrically stimulated, left guinea pig-atria and particularly on electrically stimulated papillary muscles marked positive inotropic effects are registered. They can be attributed to release of catecholamines from intracellular stores.