Role of vagus nerve-muscarinic cholinergic receptor pathway in mitigation of myocardial ischemia-reperfusion injury by intrathecal morphine postconditioning in rats / 中华麻醉学杂志

ABSTRACT

Objective evaluate the role of vagus nerve?muscarinic cholinergic receptor ( M recep?tor) pathway in mitigation of myocardial ischemia?reperfusion (I∕R) injury by intrathecal morphine postcon?ditioning in rats. Methods Seventy adult male Sprague?Dawley rats in which intrathecal catheters were suc?cessfully placed without complications, weighing 250-350 g, were randomly assigned into 7 groups ( n=10 each) using a random number tablesham operation group (Sham group), I∕R group, intrathecal morphine postconditioning group ( MP group) , vagal transection ( VT) group, VT+ intrathecal morphine postcondi?tioning group (VT+MP group), atropine (ATP, M receptor antagonist) + morphine postconditioning group ( ATP+MP group) , and ATP group. Myocardial I∕R was produced by occlusion of the anterior descending branch of left coronary artery for 30 min followed by 2 h of reperfusion. Morphine ( 3μg∕kg, 10μl) was in?trathecally infused over 5 min starting from onset of reperfusion in MP group. Normal saline 10 μl was in?trathecally infused over 5 min starting from onset of reperfusion in NS group. The bilateral vagus nerves were transected at 10 min before reperfusion in VT+MP group. Atropine ( 0?1 mg∕kg, 0?5 ml) was intravenously infused over 5 min starting from 10 min before reperfusion in ATP+MP group. The occurrence of cardiac ar? rhythmia ( premature ventricular contractions ( PVCs) and ventricular tachycardia ( VT)∕ventricular fibrilla?tion ( VF) ) within the first 30 min of reperfusion was recorded. The rats were sacrificed at 120 min of reper?fusion, and myocardial specimens were obtained for determination of myocardial infarct size ( IS) as a per?centage of area at risk (AAR). IS∕AAR ratio was calculated. Results Compared with Sham group, the number of PVCs and VT∕VF and IS∕AAR ratio were significantly increased in the other groups. Compared with I∕R group, the number of PVCs and VT∕VF and IS∕AAR ratio were significantly decreased in MP group. Compared with MP group, the number of PVCs and VT∕VF and IS∕AAR ratio were significantly in?creased in VT+MP and ATP+MP groups. Conclusion Vagus nerve?M receptor pathway is involved in miti?gation of myocardial I∕R injury by intrathecal morphine postconditioning in rats.