Effect of intrathecal dexmedetomidine pretreatment on myocardial ischemia-reperfusion injury in rats / 中华麻醉学杂志

ABSTRACT

Objective To investigate the effect of intrathecal dexmedetomidine pretreatment on my-ocardial ischemia-reperfusion (I∕R) injury in rats. Methods Forty-five adult Sprague-Dawley rats of both sexes, weighing 200-250 g, in which intrathecal catheters were successfully placed without complications, were divided into 3 groups (n= 15 each) using a random number table sham operation group (group S), group I∕R and intrathecal dexmedetomidine pretreatment group ( group DEX). Myocardial I∕R injury was produced by occlusion of the left anterior descending branch of the coronary artery for 30 min followed by 120 min reperfusion. Dexmedetomidine 1 μg∕kg (diluted to 10 μl in normal saline) was intrathecally injec-ted at 30 min before ischemia in group DEX. The equal volume of normal saline was given in group I∕R. Blood samples were collected from the cardiac apex at the end of reperfusion for measurement of plasma nor-epinephrine (NE) and cardiac troponin I ( cTnI) concentrations. Then all the rats were sacrificed, and myocardial tissues were obtained for determination of myocardical infarct size, and the spinal cord was isola-ted to detect the expression of c-fos in the spinal dorsal horn by Western blot. Results Compared with group S, the myocardical infarct size, plasma NE and cTnI concentrations were significnatly increased, and the expression of c-fos in the spinal dorsal horn was up-regulated in I∕R and DEX groups (P<0. 05). Compared with group I∕R, the myocardical infarct size, plasma NE and cTnI concentrations were signific-natly decreased, and the expression of c-fos in the spinal dorsal horn was down-regulated in group DEX (P<0. 05). Conclusion Intrathecal dexmedetomidine pretreatment can reduce myocardial I∕R injury in rats, and the mechanims may be related to decreasing plasma NE levels and inhibiting c-fos expression in the spinal dorsal horn.