Objective To investigate the effect and possible mechanism of oxytocin on the expression of NO and ET-1 in precon-ditioning myocardium of rats with ischemia .Methods The rats were randomly divided into ischemic reperfusion group(I/R) ,ische-mic reperfusion + oxytocin pretreatment group(I/R+OT) ,sham operation group(SH) and nomal control group(N) .The myocar-dial ischemia-reperfusion model was induced by 25 min coronary occlusion and 120 min reperfusion in opened-chest anesthetized rats ,rats of SH group were not conducted with ligation but threading only .Group I/R+ OT were administered oxytocin(0 .03 g/kg ,i .p)25 min prior to ischemia ,the other three groups were given the same amount normal saline .After reperfusion ,nitric oxide (NO) ,endothelin-1(ET-1) ,creatin kinase isoenzyme(CK-MB)and lactate dehydrogenase(LDH)in blood serum were measured .At the end of reperfusion ,HE stain was used to observe the morphology of the cardiac muscular tissue .Results Pathological observa-tion showed that the myocardial cell in group SH and in X ranged in order ,with no fibers fractured ,myocardial fibers in I/R group were fractured and disorganized ,interstitial edema ,neutrophil infiltration were also observed .It was more serious in group I/R than in group I/R+OT .Compared with SH group ,the CK-MB ,LDH ,ET-1 of the I/R group and I/R+OT group increased ,the NO de-creased(P<0 .05) ,and it had no difference in group N and group SH (P>0 .05) Compared with the I/R group ,in I/R+OT group the expression of CK-MB ,LDH ,ET-1 were decreased ,the level of NO increased(P<0 .05) .There was a negative correlation be-tween NO and ET-1 in group I/R and I/R+ OT (P< 0 .05) .Conclusion Oxytocin pretreatment on rat myocardial ischemia and reperfusion has protective effect ,and its action mechanisms maybe associated with the increase of the content of NO and the de-crease of the content of ET-1 in blood serum .%目的：探讨缩宫素（OT）对大鼠急性心肌缺血再灌注后一氧化氮（NO）与内皮素-1（ET-1）的影响及可能的机制。方法将大鼠随机分为心肌缺血再灌注组（I/R组）、I/R＋O T预处理组（I/R＋O T组）、假手术组（S H组）和健康对照组（N组）。采用在体大鼠结扎冠状动脉前降支25 min后，松扎再灌注120 min形成I/R模型，SH组只穿线不结扎。I/R＋ OT 组在缺血前25 min腹腔注射OT 0．03μg/kg ，其余3组给予等量生理盐水。再灌注结束后测定血清肌酸激酶同工酶（CK-MB）、乳酸脱氢酶（LDH）、NO及ET-1；再灌注结束时，采用HE染色进行心肌组织形态学分析。结果光镜下观察，N组与SH组心肌细胞排列整齐，无肌纤维破坏，I/R组心肌纤维排列不规则、断裂，心肌间质水肿，较多粒细胞灶状浸润，I/R＋O T组可见心肌细胞排列、间质水肿及粒细胞浸润程度介于N组与SH组。与SH组相比，I/R组和I/R＋ OT组血清CK-MB、LDH、ET-1升高，NO水平降低，差异均有统计学意义（P均＜0．05），而N组的表达差异无统计学意义（P＞0．05）；与I/R组相比，I/R＋OT组血清CK-MB、LDH、ET-1降低，NO水平升高，差异均有统计学意义（P均＜0．05）。I/R组和I/R＋OT组血清NO与ET-1水平呈负相关（P＜0．05）。结论 OT预处理对大鼠I/R有保护作用，其作用机制可能与OT增加血清NO水平、降低ET-1水平有关。
展开▼
