【摘要】 在大鼠心脏上同时激动α１肾上腺素受体（α１－ＡＲ）与β－肾上腺素受体的（β－ＡＲ），较单独激动β－ＡＲ时产生的ｃＡＭＰ明显减少，α１Ａ－ＡＲ亚型抑制，而α１Ｂ－ＡＲ亚型增强β－ＡＲ刺激ｃＡＭＰ生成的作用。但α１－ＡＲ及其亚型激动不影响ｆｏｒｓｋｏｌｉｎ引起的ｃＡＭＰ生成，亦不影响β－ＡＲ与［１２５Ｉ］吲哚洛尔的最大结合容量和解离常数。苯福林激动α１－ＡＲ对三磷酸鸟苷使异丙肾上腺素与［１２５Ｉ］吲哚洛尔的竞争抑制曲线右移程度无显著影响。提示α１－ＡＲ及其亚型影响β－ＡＲ心肌正性变力效应的作用发生在腺苷酸环化酶激动之前的环节，但并不影响β－ＡＲ本身及其与Ｇ蛋白的偶联。更多还原

【Abstract】 The activation of α1-adrenoceptor(α1-AR)or its subtypes affecting the β-adrenoceptor(β-AR)mediated positive inotropic response of heartin rats had been demonstrated.The possible pathwayshrthose interactions were explored;The resultsshowed that activation of both α1-AR and β-AR bynorepinephrine(NE)or isoprenaline(Iso)plusphenylephrine(PE) induced less cAMP accumulationthan that of only β-AR.α1-AR subtype selectiveantagonist WB4101(1 nmol·L-1)potentiated theβ-AR mediated stimulation of cAMP accumulation,while α1B-AR subtype selective alkylating agentchloroethvlclonidine(CEC,pre-incubation at 20μmol·L-1) inhibited it.Activation of α1-AR,however.did not influence the forskolin-inducedcAMP production. The radioligand binding assaysshowed that activation of α1-AR or either subtypeshad no effect on the maximal binding concentration(Bmax)and the affinity(Kd)of [125I]pindolol to β-AR.The Iso inhibition curve was shifted to right in the pres-ence of 100 μmol·L-1 GTP,and activation ofα1-AR showed no effect on the shift. Thus,theα1B-AR enhanced the β-AR mediated cAMP produc-tion,while the α1A-AR inhibited.And α1A-AR playeda dominant role while both subtypes were activatedsimultaneously. The results suggested that the pathwayfor α1-AR and its subtype to influence the β-AR medi-ated inotropic response located at the signaltransduction before the activation of adenyl cyclase.Activation of α1-AR and its subtypes might changethe activity of Gs protein.更多还原