title: Chronotropic effects of coronary vasodilators as assessed in the isolated, blood-perfused sino-atrial node preparation of the dog.
abstract: Chronotropic effects of 6 coronary vasodilators, carbochromen, dilazep, diltiazem, dipyridamole, nifedipine and verapamil, were compared by close-arterial administration to the isolated, blood-perfused sino-atrial node preparation of the dog. All drugs produced a dose-related decrease in sinus rate, and the order of negative chronotropic potency determined on a weight basis was as follows: (formula: see text). Higher doses of these drugs except dipyridamole caused atrial standstill. The order of potency causing atrial standstill determined on a weight basis was as follows: (formula: see text). Dipyridamole in lower doses produced a negative chronotropic effect alone, but with higher doses a positive chronotropic effect preceded a negative one. Carbochromen in a wide range of doses produced a triphasic response consisting of initial brief positive, succeeding main negative and final gradually-developing slight positive components.
mesh_terms: D000818:Animals; D003864:Depression, Chemical; D004109:Dilazep / Q000494:pharmacology; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D006339:Heart Rate / Q000187:drug effects*; D066298:In Vitro Techniques; D009543:Nifedipine / Q000494:pharmacology; D012849:Sinoatrial Node / Q000187:drug effects*; D013268:Stimulation, Chemical; D014665:Vasodilator Agents / Q000494:pharmacology*; D014700:Verapamil / Q000494:pharmacology
chemical_list: D014665:Vasodilator Agents; D014700:Verapamil; D004109:Dilazep; D009543:Nifedipine