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目的:探讨糖尿病合并高血压大鼠心脏α1肾上腺素受体(α1-AR)及其三种亚型的变化规律和可能的意义。方法:用Wistar雄性大鼠建立糖尿病合并高血压模型,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α1肾上腺素受体(α1-AR)及其三种亚型的改变。结果:与正常对照大鼠相比,糖尿病合并高血压大鼠心脏α1-AR最大结合容量(Bmax)显著增加(P<0.05),且α1A-AR和α1D-AR均增加。糖尿病合并高血压大鼠左心房α1-AR介导的最大收缩反应较对照组降低41%(P<0.05),pD2值不变。α1-AR亚型选择性拮抗剂5-MU、spiperon和BMY7378拮抗NE正性变力效应的pA2值不变。结论:糖尿病合并高血压大鼠心脏α1-AR介导的最大收缩反应的降低,其主要与受体后信号转导效应减弱有关,其中以α1A-AR和α1D-AR尤为显著。
Objective: To investigate the changes and possible significance of α1-adrenergic receptor (α1-AR) and its three isoforms in diabetic hypertensive rats. Methods: The changes of cardiac α1-adrenergic receptor (α1-AR) and its three isoforms were observed in Wistar male rats with diabetes mellitus complicated with hypertension, radioligand binding assay and isolated left atrial systolic function test. Results: Compared with normal control rats, the maximal α1-AR binding capacity (Bmax) in diabetic rats with hypertension increased significantly (P <0.05), and both α1A-AR and α1D-AR increased. The maximal contractile response induced by α1-AR in left atrium of diabetic rats with hypertension was 41% lower than that of the control group (P <0.05), while pD2 was unchanged. The α1-AR subtype selective antagonists 5-MU, spiperon and BMY7378 did not change the pA2 value of NE positive force effect. CONCLUSION: The decrease of maximal contractile response induced by α1-AR in the heart of diabetic rats with hypertension is mainly related to the weakened signal transduction effect of post-receptor, especially α1A-AR and α1D-AR.