Schümann H J
Eur Heart J. 1983 Jan;4 Suppl A:55-60. doi: 10.1093/eurheartj/4.suppl_a.55.
Ahlquist described the existence of beta-adrenoceptors as structures mediating the positive effects of sympathetic nerve stimulation in the heart. Recently, the role of alpha-adrenoceptors has also been investigated by both biological and radioligand binding studies. The presence of alpha-adrenoceptors has now been demonstrated in the hearts of various mammalian species including man. Stimulation of beta-adrenoceptors causes positive ino-, chrono-, dromo- and bathmotropic effects while that of alpha-adrenoceptors is restricted to positive inotropic effects. Analysis of the effects mediated by alpha-stimulation as carried out in our department showed a clear-cut difference between the mechanisms underlying stimulation of beta- and of alpha-adrenoceptors: that evoked by beta-adrenoceptors is connected to an increase in cAMP, whereas that by alpha-adrenoceptors is not. Moreover, the effect of alpha-stimulation is evidently more dependent on heart rate and on the presence of Ca2+ than that of beta-stimulation. The nature of cardiac alpha-adrenoceptors is apparently distinct from that of other organs as they are stimulated by dopamine and adrenaline but not by the transmitter noradrenaline. Since the alpha-receptor-mediated increase in force of contraction is obviously less energy consuming than that via beta-receptors the heart gains a greater adaptability in adrenergic regulation especially in emergency situations such as myocardial infarction.
阿尔奎斯特描述了β-肾上腺素能受体作为介导交感神经刺激对心脏产生积极作用的结构的存在。最近，α-肾上腺素能受体的作用也通过生物学和放射性配体结合研究进行了调查。现已证实在包括人类在内的各种哺乳动物的心脏中都存在α-肾上腺素能受体。刺激β-肾上腺素能受体可产生正性变力、变时、变传导和变肌张力作用，而刺激α-肾上腺素能受体则仅限于产生正性变力作用。我们科室对α-刺激介导的效应进行的分析表明，β-肾上腺素能受体和α-肾上腺素能受体刺激的潜在机制存在明显差异：β-肾上腺素能受体引起的效应与环磷酸腺苷（cAMP）增加有关，而α-肾上腺素能受体引起的效应则不然。此外，α-刺激的效应显然比β-刺激的效应更依赖心率和钙离子的存在。心脏α-肾上腺素能受体的性质显然与其他器官不同，因为它们受多巴胺和肾上腺素刺激，但不受递质去甲肾上腺素刺激。由于α受体介导的收缩力增加显然比通过β受体的收缩力增加消耗的能量少，心脏在肾上腺素能调节方面获得了更大的适应性，尤其是在心肌梗死等紧急情况下。
