Cardiovascular Effects of Acebutolol Following Coronary Artery Occlusion and Reperfusion in Anaesthetized Dog

Abstract

The effects of 5 mg/kg acebutolol given intravenously were investigated in anaesthetized dogs after (a) ligation of the left anterior descending coronary artery and (b) coronary reperfusion following 60 min of ligation of the left anterior descending coronary artery. Coronary artery ligation produced, after 4 to 6 h, persistent multiple ventricular ectopic beats and abnormalities of R and T waves and of the S‐T segment. Administration of acebutolol, after the development of persistent ventricular arrhythmias, restored normal sinus rhythm within 5 min of injection. Electrocardiographic abnormalities were also reduced. Coronary artery reperfusion (following 60 min of ligation) resulted in multiple ventricular ectopic beats, ventricular tachycardia and/or ventricular fibrillation. Pretreatment with acebutolol, 15 min before starting reperfusion, markedly reduced the arrhythmias. Acebutolol did not affect peak inspiratory airway pressure. Acebutolol produced significant bradycardia and slight, transient, hypotension. It was without effect on left ventricular systolic pressure, left ventricular end‐diastolic pressure, cardiac output or pulmonary arterial pressure. These results suggest beneficial effects of acebutolol in myocardial ischaemia and coronary reperfusion, without any significant risk of cardiodepression or bronchospasm.

Role of Oxidative Stress in the Genesis of Ventricular Arrhythmias

“…Pharmacological modulation of the beta-adrenergic receptors by propranolol, however, decreased ventricular fibrillation threshold only during ischemia but was without effect on the arrhythmias threshold during coronary artery release [ 33 ]. Likewise, other nonselective as well as selective beta-blockers have shown inconsistent beneficial effects on the ischemia/reperfusion-induced ventricular arrhythmias [ 33 , 37 , 38 , 39 , 40 , 41 , 42 ]. In fact, ventricular arrhythmias threshold, incidence and the overall severity due to the administration of excessive amount of catecholamines were not prevented by a beta-blockade [ 43 ].…”

Effect of Sotalol Against Reperfusion‐induced Arrhythmias in Sprague‐dawley and Wistar Rats

“…The susceptibility of reperfusion-induced arrhythmias to P-adrenoreceptors on the other hand is more controversial (Corr and Witkowski, 1984). For example, in the dog in vivo, acebutolol reduced the incidence of ventricular tachycardia upon reperfusion (Chernecki et al, 1978), while propranolol failed to show any effect (Naito et al, 1981 ;Lamontagne et al, 1986). This controversy can be explained by the fact that P-blockers might exert their protective effect throught local anesthetic activity.…”