Amiodarone, adrenoceptor responsiveness and ischaemia- and reperfusion-induced arrhythmias

• Published in: European journal of pharmacology Vol. 201; no. 1; p. 103
• Main Authors: Coker, S J, Chess-Williams, R
• Format: Journal Article
• Language: English
• Published: Netherlands 16.08.1991
• Subjects: Amiodarone - administration & dosage; Amiodarone - pharmacology; Animals; Arrhythmias, Cardiac - etiology; Arrhythmias, Cardiac - prevention & control; Coronary Disease - complications; In Vitro Techniques; Male; Myocardial Contraction - drug effects; Myocardial Reperfusion Injury - complications; Rats; Rats, Inbred Strains; Receptors, Adrenergic, beta - drug effects
• ISSN: 0014-2999
• DOI: 10.1016/0014-2999(91)90329-o

Experiments were performed in rats which had been pretreated with amiodarone 50 mg kg-1 day-1 p.o. for 4 weeks. In anaesthetized animals subject to 25 min of coronary artery occlusion, the rats which had received amiodarone had fewer ischaemia-induced ventricular premature beats than the controls (381 +/- 106 compared with 815 +/- 215, P = 0.070). The duration of arrhythmias induced by reperfusion following 5 min of ischaemia was also less in the rats which had received amiodarone than in the controls (43.8 +/- 6.8 and 16.0 +/- 3.1 s respectively). Pretreatment of rats with amiodarone reduced the maximum driving frequency of both isolated left atria and papillary muscles. There were no differences between the responses to alpha- or beta-adrenoceptor agonists or to calcium in papillary muscle preparations from amiodarone-pretreated and control rats. These results suggest that the antiarrhythmic activity of chronic amiodarone seen in the present study does not depend on changes in ventricular adrenoceptor responsiveness.