Effects of optical isomers of verapamil on SA nodal pacemaker activity and contractility of the isolated dog heart.
Using 10 isolated, blood-perfused canine atrial, and ventricular preparations, the effects of d- and l-verapamil on SA nodal pacemaker activity and contractility were investigated. l-verapamil and d-verapamil produced dose-related negative chronotropic and inotropic effects in all experiments. l-verapamil was approximately 10 time more potent than d-verapamil both in inotropism and chronotropism. Negative inotropism of either d- or l-verapamil can be reversed by injection of calcium chloride. Not only d-verapamil but also l-verapamil produced a stronger suppression at higher frequencies in both atrial and ventricular muscles.
D000818:Animals; D016275:Atrial Function; D002122:Calcium Chloride / Q000494:pharmacology; D003864:Depression, Chemical; D004285:Dogs; D004558:Electric Stimulation; D066298:In Vitro Techniques; D009200:Myocardial Contraction / Q000187:drug effects*; D012849:Sinoatrial Node / Q000187:drug effects / Q000502:physiology*; D013268:Stimulation, Chemical; D014700:Verapamil / Q000494:pharmacology*
D014700:Verapamil; D002122:Calcium Chloride