Effects of dibutyryl cyclic AMP on sinus rate and atrial contractile force in the isolated atrium of the dog.
In blood-perfused isolated canine atrium preparations, single injections of dibutyryl cyclic AMP at a dose range of 1 to 30 mg were made into the cannulated sinus node artery. At doses above 3 mg, dibutyryl cyclic AMP induced a biphasic chronotropic and inotropic response; there was a slight and rapid negative chronotropic and inotropic response, followed by a long-lasting positive chronotropic and inotropic response. The induction of the positive effects was slow, and it took 4 to 8 min to reach a maximum response. These effects continued 20 to 60 min. The ratios of the positive inotropic effect/positive chronotropic effect were very similar to those induced by norepinephrine. In this study, it was confirmed that a large dose of dibutyryl cyclic AMP induced a positive chronotropic and inotropic effect on the canine atrium, and the possibility was discussed that cyclic AMP may be involved in the effects of beta-adrenergic amines on the pacemaker and contractile process of the heart.
D000818:Animals; D003994:Bucladesine / Q000008:administration & dosage / Q000494:pharmacology*; D004285:Dogs; D006325:Heart Atria / Q000187:drug effects*; D006339:Heart Rate / Q000187:drug effects*; D066298:In Vitro Techniques; D012849:Sinoatrial Node / Q000187:drug effects; D013268:Stimulation, Chemical; D013997:Time Factors
D003994:Bucladesine