González Alvarez R, García Rodríguez M
Acta Physiol Lat Am. 1977;27(5):239-47.
5-hydroxytryptamine (serotonin) produces a positive chronotropic effect in the isolated atrium of the hamster. The characterization of this effect using reserpine pretreatment, propranolol, pargyline, 6-hydroxydopamine or the combination of some of those drugs enable us to conclude that serotonin is an amine of mixed action in the isolated atrium of the hamster, that is, its positive chronotropic effect has a direct component, which is obtained with lower concentrations of agonist and an indirect component through the liberation of endogenous noradrenaline from the sympathetic nerve terminals. The highest concentrations of serotonin are responsible of that component. Pargyline potentiates the indirect component of 5-HT, because inhibition of intraneuronal monoamine oxidase (MAO) avoids the degradation of the noradrenaline released, but it does not potentiate the direct component, indicating that postsynaptic cardiac MAO has little importance in the metabolism of serotonin administered exogenously.
5-羟色胺（血清素）对仓鼠离体心房产生正性变时作用。通过利血平预处理、普萘洛尔、帕吉林、6-羟基多巴胺或其中一些药物的组合对该作用进行表征，使我们能够得出结论：血清素在仓鼠离体心房中是一种具有混合作用的胺，即其正性变时作用有一个直接成分，该成分在较低浓度激动剂作用下即可产生，还有一个间接成分，是通过从交感神经末梢释放内源性去甲肾上腺素产生的。血清素的最高浓度导致该成分产生。帕吉林增强了5-羟色胺的间接成分，因为抑制神经元内单胺氧化酶（MAO）可避免释放的去甲肾上腺素降解，但它不会增强直接成分，这表明突触后心脏MAO在外源性给予的血清素代谢中作用不大。
