Yamanaka K, Kitamura K
Department of Pharmacology, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
Eur J Pharmacol. 1987 Nov 24;144(1):29-37. doi: 10.1016/0014-2999(87)90005-7.
To elucidate the role of the histamine receptor in functions related to intestinal motility, we investigated the effects of histamine and its antagonists on electrical and mechanical activities in longitudinal and circular layers of the terminal region of the guinea-pig ileum. Histamine hyperpolarized the membrane in the circular smooth muscle cells by increasing the permeability of K+ and it transiently inhibited generation of the spike while resting tone was elevated. Cimetidine (CIM) inhibited the hyperpolarization and relaxation induced by histamine while mepyramine (MEP) inhibited the contraction but did not affect the histamine-induced hyperpolarization. In the presence of CIM, histamine did not depolarize the membrane but did lower the threshold potential required for generation of the spike potential, increased the appearance of the spike and enhanced the phasic contraction. Histamine, in 20 mM K+ solution, hyperpolarized the membrane and produced a biphasic response, an initial relaxation and a subsequently generated contraction, in a concentration-dependent manner. In the longitudinal smooth muscle cells, histamine depolarized the membrane, and enhanced both generation of the spike and the contraction. MEP (0.1 microM) but not CIM (1 microM) blocked the histamine-induced responses. CIM at a higher concentration (10 microM) enhanced the histamine-induced contraction, while histamine did not relax the tissue precontracted by 20 mM K+. These results indicate that the circular muscle cells have both H1 and H2 receptors while the longitudinal muscle cells have the H1 receptor. The excitatory responses induced by activation of the H1 receptor in smooth muscle cells differ in these layers.
为阐明组胺受体在肠道运动相关功能中的作用，我们研究了组胺及其拮抗剂对豚鼠回肠末端区域纵行肌层和环行肌层电活动和机械活动的影响。组胺通过增加钾离子通透性使环行平滑肌细胞膜超极化，并在静息张力升高时短暂抑制锋电位的产生。西咪替丁（CIM）抑制组胺诱导的超极化和舒张，而美吡拉敏（MEP）抑制收缩但不影响组胺诱导的超极化。在CIM存在的情况下，组胺不会使膜去极化，但会降低产生锋电位所需的阈电位，增加锋电位的出现并增强相性收缩。在20 mM钾离子溶液中，组胺使膜超极化，并以浓度依赖的方式产生双相反应，即初始舒张和随后产生的收缩。在纵行平滑肌细胞中，组胺使膜去极化，并增强锋电位的产生和收缩。MEP（0.1 microM）而非CIM（1 microM）阻断组胺诱导的反应。较高浓度（10 microM）的CIM增强组胺诱导的收缩，而组胺不会使由20 mM钾离子预收缩的组织舒张。这些结果表明，环行肌细胞同时具有H1和H2受体，而纵行肌细胞具有H1受体。平滑肌细胞中H1受体激活诱导的兴奋性反应在这些肌层中有所不同。
