ABSTRACT
Objective To evaluate the effects of butorphanol pretreatment on myocardial damage induced by limb ischemia/reperfusion (I/R) in rats.Methods One hundred and eight male Sprague-Dawley rats,weighing 180-220 g,were randomly divided into 3 groups (n =36 each) using a random number table:sham operation group (group S),I/R group and butorphanol pretreatment group (group B).Limb ischemia was induced by occlusion of bilateral hind limbs for 2 h followed by reperfusion in I/R and B groups.At 10 min before ischemia,butorphanol 0.2 mg/kg was injected via the right jugular vein in group B,while the equal volume of normal saline was injected in group I/R.Six rats were chosen randomly before ischemia (baseline,T0) and at 2,6,12,24 and 48 h after reperfusion (T1-5) and blood samples were taken from the abdominal aorta for determination of the serum creatine kinase isoenzyme-MB (CK-MB) activity and cardiac troponin Ⅰ (cTnI) concentration.The animals were then sacrificed and myocardial specimens were obtained for determination of myocardial apoptosis (using TUNEL) and the expression of c-Jun N-terminal kinase (JNK) and extracellular signal-regulated protein kinase (ERK) (using Western blot analysis).Apoptosis index was calculated.Results Compared with group S,the serum CK-MB and cTnI levels were significantly increased at T1-5,and the apoptosis index and expression of JNK and ERK were increased at T2-5 in group I/R (P ＜ 0.05).Compared with group I/R,the pathological changes of myocardium were significantly reduced at T4,the serum CK-MB and cTnI levels were decreased at T2-5,the apoptosis index was decreased at T4,5,the expression of ERK was up-regulated at T2-5,and the expression of JNK was down-regulated at T2-4 (P ＜ 0.05).Conclusion Butorphanol pretreatment can reduce apoptosis in myocardial cells through activating MAPK signal transduction pathway,up-regulating ERK expression and down-regulating JNK expression,thus attenuating myocardial damage induced by limb I/R in rats.