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本文用放射配体结合实验研究了α１－肾上腺素受体（α１－ＡＲ）及亚型在大鼠左心房的分布。结果表明，大鼠左心房α１－ＡＲ有α１Ａ与α１Ｂ两种亚型，α１Ａ亚型约占１／３，α１Ｂ亚型占２／３。离体灌流左心房功能实验结果表明，α１－ＡＲ不同亚型对β肾上腺素受体（β－ＡＲ）所介导的正性变力反应具有不同性质的协同作用。当酚妥拉明１０μｍｏｌ／Ｌ同时阻断α１Ａ与α１Ｂ亚型时，ＮＥ（同时激动α１－与β－ＡＲ）的剂量－收缩效应曲线显著左移，当用ＣＥＣ２０μｍｏｌ／Ｌ预处理以阻断α１Ｂ亚型时，ＮＥ的剂量－收缩效应曲线则显著右移，而用ＷＢ４１０１１ｎｍｏｌ／Ｌ阻断α１Ａ亚型后，ＮＥ的剂量－收缩效应曲线出现左移；此外，当用苯肾上腺素激动α１－ＡＲ时，异丙肾上腺素的剂量－收缩效应曲线亦显著右移。提示α１Ａ亚型可抑制β－ＡＲ介导的正性变力效应，而α１Ｂ亚型则可增强β－ＡＲ所介导的反应，但当α１－ＡＲ的上述两种亚型同时激动时，则以α１Ａ亚型的调节作用为主。
Radioligand binding experiments were used to investigate the distribution of α1-adrenoceptors (α1-AR) and its subtypes in the left atrium of rats. The results showed that α1A and α1B subtypes were present in the left atrium of the rat, accounting for about 1/3 of the α1A subtype and 2/3 of the α1B subtype. The experimental results of left atrial function in vitro perfusion showed that different subtypes of α1-AR have different synergistic effects on the positive force reaction mediated by β-adrenergic receptor (β-AR). When phentolamine 10 μmol / L blocked both α1A and α1B subtypes, the dose-contraction effect curve of NE (simultaneous agonistic α1- and β-AR) shifted significantly to the left. When pretreated with CEC 20 μmol / L to block α1B The dose-contraction effect curve of NE was significantly shifted to the right subtype, while the dose-contraction effect curve of NE appeared to shift to the left when WB41011nmol / L was used to block α1A subtype. In addition, when phenylephrine was used to agonize α1-AR , The isoproterenol dose-contraction effect curve also shifted significantly to the right. The results suggest that α1A subtype inhibits the β-AR-mediated positive force effect, whereas α1B subtype enhances β-AR-mediated responses. However, when the two subtypes of α1-AR are agonized simultaneously, Α1A subtype regulation mainly.