Effects of butorphanol pretreatment on myocardial ischemia-reperfusion injury in rats

Abstract

Objective To investigate the effects of butorphanol pretreatment on myocardial ischemia-reperfusion (IR) injury in rats. Methods Forty healthy male SD rats weighing 200-250 g were randomly divided into 5 groups (n = 8 each) : sham operation group (group S); IR group; butorphanol pretreatment group (group B); Nor-BNI group (group N) and glibenclamide group (group G) . In group IR, B, N and G, myocardial IR was produced by occlusion of left anterior descending artery (LAD) for 30 min followed by 120 min reperfusion. In group S and IR, normal saline S ml/kg was injected via femoral vein 10 min before ischemia and then continuously infused at a rate of 5 ml· kg -1· h-1 iv. In group B, butorphanol 25 μg/kg was injected via femoral vein 10 min before ischemia and the rest method was the same as that described in group IR. In group N, Nor-BNI 2 mg/kg (a selective κ-opioid receptor antagonist) was injected via femoral vein 20 min before ischemia and the rest method was the same as that described in group B. In group G, glibenclamide 1 mg/kg (a KATP channel blocker) was injected via femoral vein 10 min before ischemia and the rest method was the same as that described in group B. Blood samples were taken from femoral artery at 120 min of reperfusion for determination of the concentrations of serum TNF-α, IL-6 and IL-10 by ELISA. Myocardial infarct area and ischemic area were measured by TTC staining and myocardial infarct size was calculated. Results The concentrations of serum TNF-a, IL-6 and IL-10 were significantly higher in the other four groups than in group S (P < 0.05) . The concentrations of serum TNF-α andIL-6 were significantly decreased while IL-10 increased, and the myocardial infarct size was significantly decreased in group B, N and G as compared with group IR ( P < 0.05) . The concentrations of serum TNF-α and IL-6 were significantly increased while the concentration of IL-10 decreased) and the myocardial infarct size was significantly increased in group N and G as compared with group B ( P < 0.05). Conclusion Butorphanol pretreatment can protect the myocardium against IR injury in rate via activating κ receptor and KATP channel. Key words: Butorphanol; Myocardial reperfusion injury; Receptors, opioid, kappa; KATP chan-nels