Elizalde A, Perez-Chavez J, Sánchez-Chapula J
Can J Physiol Pharmacol. 1986 Dec;64(12):1484-8. doi: 10.1139/y86-250.
The effects of histamine on the force of contraction and calcium-dependent action potentials were studied in rabbit ventricular papillary muscles. The positive inotropic effect of histamine seems to be dependent on stimulation of H1 and H2 receptors. The H1 antagonist chlorpheniramine produced a competitive blockade of the positive inotropic effects of histamine. Cimetidine produced a competitive blockade, which was apparent only after blockade of H1 receptors. Histamine increased the maximum upstroke velocity of slow action potentials. This effect can be entirely accounted for by stimulation of H2 receptors. The phosphodiesterase inhibitor 3-isobutyl-methyl-xanthine potentiated the H2 receptor mediated effects of histamine on the force of contraction and slow action potentials. We conclude that rabbit ventricular muscle possesses both H1 and H2 receptors that mediate the positive inotropic effect of histamine. The H2-mediated effect seems to be causally related to an increase in the calcium slow inward current and is probably linked to an enhanced cellular cyclic adenosine monophosphate content. The mechanism of the H1-mediated positive inotropic effect remains unknown.
在兔心室乳头肌中研究了组胺对收缩力和钙依赖性动作电位的影响。组胺的正性肌力作用似乎依赖于H1和H2受体的刺激。H1拮抗剂氯苯那敏对组胺的正性肌力作用产生竞争性阻断。西咪替丁产生竞争性阻断，仅在H1受体被阻断后才明显。组胺增加了慢动作电位的最大上升速度。这种作用完全可以通过刺激H2受体来解释。磷酸二酯酶抑制剂3-异丁基-甲基黄嘌呤增强了组胺对收缩力和慢动作电位的H2受体介导的作用。我们得出结论，兔心室肌同时具有介导组胺正性肌力作用的H1和H2受体。H2介导的作用似乎与钙慢内向电流的增加有因果关系，并且可能与细胞内环磷酸腺苷含量的增加有关。H1介导的正性肌力作用机制尚不清楚。
