Tyramine的升压作用乃因促进Noradrenaline释放的结果,已被许多研究者证明。但最近发现Tyramine能降低整个大白鼠心脏的Catecholamine的含量。作者用离体的和阿托品化的大白鼠心房证明Bretylium,Guanethidine和Tyramine都有正性肌力作用。如果预先以利血平处理或将Dichloroisprenaline加入浴器中,则这些反应即可消失。如果组织中仍有Noradrenaline则虽用利血平处理,其正性肌力作用仍然存在。作者因而推论:Bretylium,Guanethidine及 Tyramine’s boost is due to the release of Noradrenaline and has been shown by many investigators. However, Tyramine was recently found to reduce Catecholamine levels in the entire rat heart. The authors demonstrate that both inotropic and atropine-induced atrial fibrillation in rats have an inotropic effect on Bretylium, Guanethidine, and Tyramine. These reactions disappear if pre-reserpine or Dichloroisprenaline is added to the bath. If the organization is still Noradrenaline, although the treatment with reserpine, the positive inotropic effect still exists. The authors therefore infer: Bretylium, Guanethidine and