长期糖尿病大鼠心脏肾上腺素受体及其介导的功能的变化

Changes of Cardiac Adrenoceptor and Its Relation with Cardiac Function in Long-term Diabetic Rats

目的:探讨长期糖尿病大鼠心脏肾上腺素受体(AR)的改变及其与心功能变化之间的关系。方法:采用链脲佐菌素(STZ)注射造成胰岛素依赖性糖尿病大鼠模型,放射配体结合实验和离体左心房收缩功能实验等方法观察心脏AR及功能的改变。结果:与同龄对照大鼠相比,糖尿病大鼠心脏β-AR的最大结合容量(Bmax)下降34%(P<0.05),KD值不变;心脏α1-AR Bmax无显著改变。糖尿病大鼠左心房β-AR介导的最大收缩反应(Rmax)较对照组下降64%(P<0.05);α1-AR介导的最大收缩反应增加36 %(P<0.05),pD2值不变。结论:长期糖尿病大鼠心脏β-AR介导的最大收缩反应降低,其可能与β-AR数量减少有关。α1-AR介导的最大收缩反应代偿性增强,其可能与受体后信号转导效应增强有关。

Objective： To study the changes of cardiac adrenoceptor （AR） and its relation with cardiac function in long-term diabetic rats. Methods： The model of diabetic rats was induced by streptozotocin （STZ）, and the levels of cardiac AR （β-AR and/or α1-AR） and cardiac function were detected by radioligand binding assays and functional determination of isolated left atria. Results： Compared with the control, the β-AR density （Bmax） was decreased by 34 % （P〈0.05） and the KD value was not changed in diabetic rats, then the Bmax of α1-AR was not altered significantly （P〉0.05）. The maximal positive inotropic response （Rmax） induced by isoproterenol in left atria of rat was decreased by 64 % （P〈0.05）. Rmax mediated α1-AR was increased by 36 % （P〈0.05）, and pD2 value was not altered in isolated elective field driven left atria of diabetic rats. Conclusion： The results suggested that the cardiac Rmax of left atria was decreased in diabetic rat. This may be associated with the decreased Bmax of β-AR. That the Rmax compensatiom mediated by cardiac α1-AR increased in diabetic rat may be associated with the enhancement of post-receptor signal transduction.