自发性高血压大鼠心脏α_1肾上腺素受体及其亚型的改变

Alterations of cardiac α 1-adrenoceptor and its subtypes in spontaneously hypertensive rats

目的：观察４月龄自发性高血压大鼠（ＳＨＲ）心脏α１肾上腺素受体（α１－ＡＲ）及其３种亚型分布与功能的改变。方法：采用离体左心房收缩功能实验和放射配体结合实验。结果：ＳＨＲ与Ｗｉｓｔａｒ大鼠相比，（１）心脏α１－ＡＲ总密度无显著变化，但对去甲肾上腺素（ＮＥ）的敏感性显著增加（Ｐ＜００５）；（２）心脏α１Ａ－ＡＲ数量无明显改变，而α１Ｂ－ＡＲ增加，α１Ｄ－ＡＲ减少，但３种亚型受体在介导ＮＥ所致心肌正性变力效应中均无显著改变。结论：提示ＳＨＲ心脏α１－ＡＲ对ＮＥ敏感性的增加可能与受体后信号转导和／或兴奋收缩耦联的增强有关。

AIM and METHODS:Alterations of density and function of cardiac α 1-adrenoceptor and its three subtypes were studied by radioligand binding assay and inotropic response measurement in spontaneously hypertensive rats(SHR) and Wistar rats.RESULTS:Compared with Wistar rats,in SHR (1) The density of cardiac α 1-adrenoceptor was unchanged,with higher potency of α 1-adrenoceptor-mediated positive inotropic response( P <0 05);(2)Ratio of the three subtypes of cardiac α 1-adrenoceptor were changed,α 1B increased,α 1D decreased and α 1A not altered The contribution of each subtype to the agonist-induced response were unchanged.CONCLUSION:The higher potency of α 1-adrenoceptor-mediated positive inotropic response may be result from enhanced efficiency of postreceptor signal transduction and/or excitation-contraction coupling, especially in α 1D -adrenoceptor.