Electrophysiological properties of SD-3211, a novel putative Ca2+ antagonist, in isolated guinea pig and rabbit hearts.

摘要: The cardiac effects of SD-3211, a novel non-dihydropyridine type Ca2+ antagonist, were examined in isolated guinea pig and rabbit hearts using an electrophysiological technique. SD-3211 (10(-6)-10(-5) M) shortened the action potential duration papillary muscles concentration-dependent manner without affecting resting or maximum upstroke velocity (Vmax). Vmax slow responses induced by high extracellular K+ isoproterenol was inhibited at concentrations greater than 10(-6) M. Elevation 2 mM reversed this response. inhibitory effect on response enhanced as stimulation frequency increased. In Langendorff-perfused electrically driven 2.0 Hz, (10(-8)-10(-6) produced prolongation atrium-His bundle conduction time (A-H interval) well reduction developed tension ventricular muscle, whereas did not affect His bundle-ventricular (H-V significantly. potency A-H those diltiazem bepridil, but weaker nicardipine, nifedipine, verapamil. interval more pronounced higher frequencies. intermediate between nicardipine verapamil its intensity frequency-dependent interval. These results suggest that has preferential channels.