急性心力衰竭大鼠心肌intermedin受体的变化

目的 观察心肌浆膜上新发现的血管活性肽intermedin（IMD）受体在异丙肾上腺素诱导心肌缺血损伤中的变化及意义.方法 在异丙基肾上腺素（isoproterenol,ISO）诱导的大鼠心肌缺血损伤模型实验组和假手术对照组,采用Western blot方法检测IMD蛋白水平,放射性配基结合技术,测定大鼠心肌浆膜上IMD 受体的结合能力.结果 ISO处理大鼠心脏呈现广泛心内膜下心肌坏死;血浆LDH活性、心肌和血浆MDA含量比对照组明显增加（均P＜0.01）;心功能明显降低,呈现严重心衰表现;IMD蛋白表达降低4倍（P＜0.01）;受体数目（Bmax）上调118% （P＜0.01）,受体与配体解离常数（Kd）比对照组增加（P＜0.05）.结论 心肌缺血性损伤引起心肌浆膜IMD蛋白表达降低、受体增加,其变化可能参与心肌损伤的发病过程.

Alteration of Intermedin Receptors in Rat with Acute Heart Failure

Objective To investigate the alteration of functional receptors for intermedin in acute myocardial injury induced by isoproterenol(ISO) in rats.Methods Myocardial ischemia injury in rats was induced by subcutaneous injection with ISO(60 mg/kg/day,3days),as experimental group,sham operation group as control.Intermedin(IMD) protein levels in ventricular tissues were examined by Western blot analysis.IMD binding sites in myocardial sarcolemma were determined by radioligand assay.Results Rats treated with ISO,histological sections showed severe myocardial ischemic injury.The plasma LDH activity,plasma MDA content and myocardial MDA content were higher than controls(all P<0.01).Heart function decreased greatly and severe heart failure was observed.Western blot analysis revealed that the IDM protein level in ISOinduced rats was 4-folds lower than that of controls.IMD receptors were up-regulated by 118 %(P< 0.01),While the affinity to apelin was decreased(Kd increased by 34%,P<0.05).Conclusion These results suggest that IDM protein level is down-regulated and the IMD receptor system is up-regulated in ISO-induced myocardial ischemic injury.These changes probably are involved in the development of cardiac injury.