Inotropic and electrophysiological actions of verapamil and D 600 in mammalian myocardium. III. Effects of the optical isomers on transmembrane action potentials.

Excitability, maximum velocity of depolarization (MVD), conduction velocity, discharge rate and the duration of transmembrane action potentials as a function of frequency of stimulation were studied in isolated cardiac tissues exposed to the optical isomers of verapamil and D 600.