大鼠左心耳三种亚型α_1肾上腺素受体对β肾上腺素受体正性变力效应的不同影响

采用电驱动离体大鼠左心耳收缩功能实验研究三种亚型α１－肾上腺素受体（ＡＲ）激动时对β－ＡＲ介导正性变力效应的影响． 结果发现，ＲＳ１７０５３（选择性拮抗α１Ａ－ＡＲ）或ＷＢ４１０１（选择性拮抗α１Ａ－和α１Ｄ－ＡＲ）可使去甲肾上腺素（ＮＥ）的累积浓度－收缩效应曲线（ＣＲＣ）显著左移；在ＢＭＹ ７３７８（选择性拮抗α１Ｄ－ＡＲ）和ＲＳ１７０５３ 存在下，ＮＥ仅激动α１Ｂ－和β－ＡＲ，其ＣＲＣ较单独激动β－ＡＲ 时显著左移；在ＷＢ４１０１ 和去氧肾上腺素（Ｐｈｅ）同时存在下（仅激动α１Ｂ－ＡＲ），异丙肾上腺素（Ｉｓｏ）的ＣＲＣ较对照显著左移；用ＢＭＹ ７３７８ 阻断α１Ｄ－ＡＲ后，ＮＥ的ＣＲＣ不发生明显的偏移；用ＲＳ１７０５３ 和螺哌隆阻断α１Ａ－和α１Ｂ－ＡＲ，用Ｐｈｅ 仅激动α１Ｄ－ＡＲ 时，对Ｉｓｏ 的ＣＲＣ也无影响． 结果说明在大鼠左心耳α１Ａ－ＡＲ抑制，α１Ｂ－ＡＲ 增强，而α１Ｄ－ＡＲ则不参与对β－ＡＲ 介导正性变力效应的调节．

Different effects of activation of three α 1 adrenoceptor subtypes on β adrenoceptor mediated positive inotropic response in isolated left rat atria 1

The effect of activation of three α 1 adrenoceptor(AR) subtypes on β AR mediated positive inotropic response was investigated in isolated electrically driven rat left atria. The results showed that the norepinephrine(NE) induced concentration response curve was shifted to the left significantly in the presence of RS 17053 10 nmol·L -1 or WB 4101 1 nmol·L -1 . When the α 1B AR was selectively activated in the presence of α 1A and α 1D AR antagonists, the concentration response curves for β AR agonists were significantly shifted to the left. The concentration response curve for NE was not significantly shifted in the presence of BMY 7378 50 nmol·L -1 . When the α 1D AR was selectively activated by phenylephrine in the presence of α 1A and α 1B AR antagonists, the isoprenaline induced concentration response curve was not significantly shifted. These results suggest that α 1A AR inhibit, α 1B AR potentiate, while α 1D AR have no effect on the positive inotropic response mediated by β AR.