Effect Of Non-excitatory Electrical Stimulation On Acute Myocardial Ischemia/reperfusion Injury In Rat

Objective:This study investigated the effects of ventricular non-excitatory electrical stimulation(NES), as pre- and post-conditioning interventions, on myocardial ischemia/reperfusion(I/R) injury in rats. Methods:Male SD rats were divided into 4 groups, normal group, I/R group(I/R), NES preconditioning group(Pre-s) and NES postconditioning group(Post-s). Animals in I/R group were subjected to 30 min of myocardial ischemia followed by 60 min reperfusion. For the Pre-s group, NES was started at 15 min before coronary artery occlusion(CAO) and continued to the end of reperfusion. For the Post-s group, NES was commenced at 5 min before re-opening of coronary circulation till the end of the reperfusion. Mean aeterial pressure(MAP), heart rates(HR) and electrocardiogram(ECG) were recorded. Arrhythmia, including ventricular ectopic beats(VEBs), ventricular tachycardia(VT) and fibrillation(VF), was evaluated. Infarct size and apoptosis of the myocardium were examined. And potential mechanism was investigated by analysis of the alterations of Cx43, SP, CGRP, NF-κB and Caspase-3 activity. Results:Compared with normal group, there were significant increases in the parameters of infarct size, apoptosis rate and the levels of Cx43, SP, CGRP(all p<0.05). The NES(both pre-and post-conditioning) could reversion the trend above and down-regulation the NF-κB m RNA and Caspase-3 activity(all p<0.05) without evoking increase of VT/VF or disturbance in hemodynamics. Conclusions:NES(both pre-and post-conditioning), as a intervention, could reduce the infarct size and apoptosis of myocardium induced by myocardial ischemia and reperfusion. The cardio-protection induced by NES may be associated with the suppression of Cx43, SP, CGRP, NF-κB and Caspase-3 activity in I/R injury.