Hemodynamic effects of dibutyryl cyclic GMP in anesthetized dogs

Dibutyryl cyclic GMP was given intravenously to anesthetized dogs with doses of 0.0625, 0.125, 0.25, 0.5 and 1.0 mg/kg, respectively. It induced decreases in blood pressure, heart rate, max LV dp/dt and total peripheral resistance with increase of stroke volume in a dose-dependent manner. Although these effects began to appear 30 sec after the administration in each dose, the duration of the effect was observed 50 sec after the administration. Effects of 1 mg/kg dibutyryl cyclic GMP on mean blood pressure and max LV dp/dt were almost equal to those of 3 micrograms/kg acetylcholine, but dibutyryl cyclic GMP was revealed to have a slower onset and longer acting effects than acetylcholine. The administration of atropine did not block the effect of dibutyryl cyclic GMP but blocked those of acetylcholine. These results indicate that dibutyryl cyclic GMP does not exert these effects through muscarinic receptors in spite of its acetylcholine-like effects.