Vohra M M
Agents Actions. 1979 Oct;9(4):319-26. doi: 10.1007/BF01970655.
The effect of histamine on adrenergic neurotransmission in the mouse isolated vas deferens preparation was investigated. Concentrations of histamine ranging from 0.2 to 650 microM depressed, in a dose-related manner, not only the contractile response elicited by field stimulation but also the response caused by the addition of exogenous noradrenaline and acetylcholine. However, the release of [3H]-NA evoked by field stimulation or by high K+ remained unchanged in the presence of these concentrations of histamine. The inhibitory effect of histamine on the contractile responses caused by various stimuli was reduced or completely antagonized by cimetidine, a histamine H2-receptor antagonist but not by mepyramine, a conventional antihistamine. The inhibitory effect of histamine was found to be inversely proportional to both the Ca2+ concentration in the bathing medium and to the frequency of field stimulation. Further, the inhibitory effect of histamine was markedly reduced when Mg2+ was omitted from the bathing medium. It is concluded that the mouse vas deferens preparation contains a post-junctional inhibitory H2-receptor. The stimulation of H2-receptors by histamine inhibits the contractile response of the vas deferens, possibly by decreasing the availability of Ca2+ required for contraction by depressing the influx of Ca2+.
研究了组胺对小鼠离体输精管标本中肾上腺素能神经传递的影响。组胺浓度在0.2至650微摩尔范围内，不仅以剂量相关的方式抑制了场刺激引起的收缩反应，还抑制了添加外源性去甲肾上腺素和乙酰胆碱所引起的反应。然而，在这些组胺浓度存在的情况下，场刺激或高钾引起的[3H]-去甲肾上腺素释放保持不变。组胺对各种刺激引起的收缩反应的抑制作用被组胺H2受体拮抗剂西咪替丁降低或完全拮抗，但未被传统抗组胺药美吡拉敏拮抗。发现组胺的抑制作用与浴液中Ca2+浓度和场刺激频率均呈反比。此外，当浴液中省略Mg2+时，组胺的抑制作用明显降低。结论是小鼠输精管标本含有一种节后抑制性H2受体。组胺对H2受体的刺激抑制了输精管的收缩反应，可能是通过抑制Ca2+内流来降低收缩所需的Ca2+可用性。
