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目的和方法：采用１２５Ｉ－ＢＥ２２５４放射配基结合实验和离体灌流左心房收缩功能实验，观察１２月龄自发性高血压大鼠（ＳＨＲ）心脏α１肾上腺素受体（α１－ＡＲ）３种亚型的分布及其介导的正性变力效应的改变。结果：ＳＨＲ与年龄匹配的Ｗｉｓｔａｒ大鼠相比，（１）心脏α１－ＡＲ最大结合容量显著增加；去甲肾上腺素（ＮＥ）通过激动α１－ＡＲ引起的累积浓度－收缩效应曲线显著左移；（２）ＢＭＹ７３７８和ＷＢ４１０１的高亲和性位点所占百分比显著增大，而（＋）ｎｉｇｕｌｄｉｐｉｎｅ不变；（３）经ＣＥＣ预处理引起ＮＥ累积浓度－收缩效应曲线右移的程度显著增加，ＢＭＹ７３７８和ＷＢ４１０１拮抗ＮＥ介导正性变力效应的ｐＡ２值均显著增大。结论：ＳＨＲ较同龄Ｗｉｓｔａｒ大鼠心脏α１－ＡＲ总数增多，对ＮＥ的敏感性显著增高，α１Ｄ－ＡＲ不仅数量增多，而且在介导收缩效应中的作用亦显著增大。
PURPOSE AND METHODS: The effects of 125I-BE2254 radioligand binding assay and isolated perfused left atrial systolic function were used to investigate the effects of α1-adrenergic receptor (α1-AR) on the 12-month-old spontaneously hypertensive rats Type distribution and the change of its positive positive force effect. Results: Compared with age-matched Wistar rats, (1) the maximal cardiac α1-AR binding capacity was significantly increased; and the cumulative concentration-contractile response curve induced by norepinephrine (NE) (2) The percentage of high-affinity sites of BMY7378 and WB4101 increased significantly, while (+) niguldipine was not changed; (3) The extent of right shift of NE accumulation-contraction effect curve was significantly increased by CEC pretreatment, The pA2 values of BMY7378 and WB4101 antagonizing NE-mediated positive force were significantly increased. CONCLUSIONS: Compared with Wistar rats of the same age, SHR increased the total number of α1-AR and increased the sensitivity to NE. Not only the number of α1D-AR increased but also the effect of mediating the contractile effect.