Carr S R, Fozard J R
Eur J Pharmacol. 1982 Jul 16;81(3):469-77. doi: 10.1016/0014-2999(82)90112-1.
Apomorphine inhibited chronotropic responses of the isolated rabbit heart to 5-HT by 40% at 1.17 micrometers and by 90% at 4.68 micrometers and strongly inhibited the outflow of 3H following preloading of hearts with [3H]- (-)-noradrenaline. Apomorphine, 4.68 micrometers, had no significant effects on transmitter release evoked by DMPP or tyramine but inhibited the responses to SNS at frequencies up to 3.2 Hz. The inhibitory effects of apomorphine on 5-HT were resistant to blockade by chlorpromazine, 1.4 micrometers, haloperidol, 1.6 micrometers, spiroperidol, 2.5 micrometers, or yohimbine, 2.8 micrometers. In contrast, the inhibitory effects of apomorphine on low frequency SNS were abolished by yohimbine. On the guinea-pig ileum treated with methysergide, apomorphine, 1.17-4.68 micrometers, blocked the indirect cholinergic responses to 5-HT less markedly than it blocked the indirect sympathomimetic responses to 5-HT on the rabbit heart. Moreover, the effects were non-selective since responses to DMPP and transmural stimulation of the intramural cholinergic nerves were similarly reduced. Modification of 5-HT receptor function is the most likely explanation for the action of apomorphine with the differential effect on 5-HT in the heart and ileum reflecting differences in the receptors and/or post receptorial events at the two sites.
阿扑吗啡在浓度为1.17微摩尔时，可使离体兔心脏对5-羟色胺的变时反应抑制40%，在浓度为4.68微摩尔时抑制90%，并且在心脏预先用[3H]-（-）-去甲肾上腺素预负荷后，能强烈抑制3H的流出。浓度为4.68微摩尔的阿扑吗啡对由二甲基苯基哌嗪（DMPP）或酪胺诱发的递质释放无显著影响，但在频率高达3.2赫兹时抑制对交感神经系统（SNS）的反应。阿扑吗啡对5-羟色胺的抑制作用不受1.4微摩尔氯丙嗪、1.6微摩尔氟哌啶醇、2.5微摩尔螺哌啶醇或2.8微摩尔育亨宾的阻断。相反，育亨宾可消除阿扑吗啡对低频交感神经系统的抑制作用。在用美西麦角处理的豚鼠回肠上，浓度为1.17 - 4.68微摩尔的阿扑吗啡阻断对5-羟色胺的间接胆碱能反应，其明显程度低于阻断兔心脏上对5-羟色胺的间接拟交感神经反应。此外，这些作用是非选择性的，因为对DMPP和壁内胆碱能神经的透壁刺激的反应同样降低。5-羟色胺受体功能的改变最有可能解释阿扑吗啡的作用，其对心脏和回肠中5-羟色胺的不同作用反映了两个部位受体和/或受体后事件的差异。
