Antiarrhythmic effects of bupuranolol against canine ventricular arrhythmias induced by halothane-adrenaline or two-stage coronary ligation.
We compared the beta-adrenoceptor blocking actions of bupuranolol and propranolol using the response to isoprenaline of the strength of contraction of the canine blood-perfused ventricular muscle, of the rate and strength of contraction of the isolated guinea pig heart and of a guinea pig tracheal ring preparation. The potency ratios of bupuranolol to propranolol were 3.6, 3.0, 3.4, and 2.4, respectively. Bupuranolol decreased the maximum dV/dt of the canine ventricular action potential and had no sympathomimetic action. Bupuranolol effectively suppressed halothane-adrenaline ventricular arrhythmias in the dog, reflecting its potency as a beta-adrenoceptor antagonist. In contrast, bupuranolol did not suppress ventricular arrhythmias induced by two-stage coronary ligation in the dog. Compared to propranolol and certain other antiarrhythmic drugs, bupuranolol had weaker effects on prolonging the effective refractory period than on the maximum dV/dt of canine ventricular muscle. This suggests that lengthening of the refractory period may be important for suppressing the two-stage coronary ligation arrhythmia and that the mechanism of this arrhythmia might be reentry.
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000818:Animals; D000889:Anti-Arrhythmia Agents; D001145:Arrhythmias, Cardiac / Q000139:chemically induced / Q000188:drug therapy* / Q000209:etiology / Q000503:physiopathology; D002046:Bupranolol / Q000494:pharmacology*; D003331:Coronary Vessels / Q000502:physiology; D004285:Dogs; D004558:Electric Stimulation; D004837:Epinephrine / Q000494:pharmacology; D006221:Halothane / Q000494:pharmacology; D006321:Heart / Q000187:drug effects; D008026:Ligation; D008839:Microelectrodes; D009200:Myocardial Contraction / Q000187:drug effects; D011412:Propanolamines / Q000494:pharmacology*
D000319:Adrenergic beta-Antagonists; D000889:Anti-Arrhythmia Agents; D011412:Propanolamines; D002046:Bupranolol; D006221:Halothane; D004837:Epinephrine