Luo X X, Tan Y H
Department of Pharmacology, Fourth Military Medical University, Xi-an, China.
Zhongguo Yao Li Xue Bao. 1994 Jan;15(1):60-4.
The action of (R)-alpha-methylhistamine (alpha-MeHA), a selective H3-receptor agonist, on field stimulation induced contraction of guinea pig vas deferens was composed of 2 components: the "inhibition" (0.1-100 nmon.L-1) and the "enhancement" (1-10 mumol.L-1). In the presence of histamine H1 antagonist, chlorpheniramine (1 mumol.L-1), alpha-MeHA (0.1 nmol.L-1-10 mumol.L-1) showed only a concentration-dependent inhibition. Selective histamine H3-receptor antagonist, thioperamide (1 nmol.L-1-10 mumol.L-1) antagonized the inhibitory effect of alpha-MeHA and increased the contractile amplitude of vas deferens elicited by field pulses when thioperamide was used alone. alpha-MeHA 10 mumol.L-1 enhanced the contractile amplitude, which was reversed by chlorpheniramine 1 mumol.L-1, but not by ranitidine (1 mumol.L-1). Pyridelethylamine, an H1-receptor agonist, facilitated concentration-dependently the contractile response of vas deferens. The effect was antagonized by chlorpheniramine, but not by ranitidine. Dimaprit, an H2-receptor agonist had no effect on the field stimulation induced sympathetic response. Both alpha-MeHA and pyridelethylamine failed to influence the contraction of vas deferens elicited by direct field stimulation in smooth muscle or by exogenously applied norepinephrine. It was concluded that histamine H1- and H3-receptors existed in sympathetic terminals of guinea pig vas deferens and facilitated or inhibited the sympathetic neurotransmission.
选择性H3受体激动剂（R）-α-甲基组胺（α-MeHA）对豚鼠输精管场刺激诱导的收缩作用由两个部分组成：“抑制”（0.1 - 100 nmol·L-1）和“增强”（1 - 10 μmol·L-1）。在组胺H1拮抗剂氯苯那敏（1 μmol·L-1）存在的情况下，α-MeHA（0.1 nmol·L-1 - 10 μmol·L-1）仅表现出浓度依赖性抑制作用。选择性组胺H3受体拮抗剂硫代哌啶（1 nmol·L-1 - 10 μmol·L-1）拮抗α-MeHA的抑制作用，并在单独使用硫代哌啶时增加场刺激引起的输精管收缩幅度。10 μmol·L-1的α-MeHA增强了收缩幅度，这被1 μmol·L-1的氯苯那敏逆转，但未被雷尼替丁（1 μmol·L-1）逆转。H1受体激动剂吡啶乙胺浓度依赖性地促进输精管的收缩反应。该作用被氯苯那敏拮抗，但未被雷尼替丁拮抗。H2受体激动剂二甲双胍对场刺激诱导的交感反应无影响。α-MeHA和吡啶乙胺均未影响平滑肌直接场刺激或外源性应用去甲肾上腺素引起的输精管收缩。结论是组胺H1和H3受体存在于豚鼠输精管的交感神经末梢，促进或抑制交感神经传递。
