Effect of ramipril on the electrophysiological characteristics of ventricular myocardium after myocardial infarction in rabbits

Aims The current study aims to explore the effect of ramipril on the occurrence of ventricular arrhythmias and its possible mechanism after myocardial infarction (MI) in rabbits. Methods A total of 24 rabbits were divided into three groups: the sham operation group (SHAM), the MI group, and the ramipril group (RAM). All groups were subjected to thoracotomy under sterile conditions; the MI and RAM groups underwent ligation of the left anterior descending coronary artery. On the second day after surgery, the RAM group was given ramipril (1 mg/kg per day). The rabbits in each group were fed for 12 weeks. The monophasic action potentials of the epicardium, mid-myocardium and endocardium in each group were, respectively, recorded before the MI and at 12 weeks after the MI. Meanwhile, the episodes of ventricular tachycardia or fibrillation (VT/VF) induced by procedure stimulations were counted, and the changes in L-type Ca2+ flux (Ica-L) were recorded by means of the whole-cell patch-clamp technique. Results The episodes of VT/VF were decreased in the RAM group after MI. At 12 weeks after MI, the transmural dispersion of repolarization (TDR) in the MI group was prolonged significantly compared with the SHAM and RAM groups. The density of Ica-L in the MI group was significantly lower than that any other group. Conclusions Ramipril manifestly decreases the incidence of VT/VF after MI in rabbits, and the mechanism may be associated with its inhibitory effect on electrical remodeling after MI.