Thorndyke M, Holmgren S
Biology Department, Royal Holloway and Bedford New College, University of London, U.K.
Regul Pept. 1990 Sep 10;30(2):125-35. doi: 10.1016/0167-0115(90)90053-y.
The interaction between bombesin and acetylcholine acting on smooth muscle of the stomach wall was investigated in two species of teleost fish. Oncorhynchus mykiss (rainbow trout) and Gadus morhua (Atlantic cod). Acetylcholine or bombesin alone has an excitatory effect on the stomach muscle. The effect on contraction amplitude of acetylcholine (10(-6)-10(-5) M) alone is about 10-times greater than the effect of bombesin (10(-9)-10(-7) M). In molar terms however, bombesin is more potent than acetylcholine. Bombesin (10(-8)-10(-7) M) added 0.5-3 min prior to acetylcholine potentiates the effect of acetylcholine in a dose-dependent manner. The potentiation is most pronounced in circular muscle preparations, but is present also in longitudinal muscle preparations. Bombesin affects the response to carbachol (10(-6) M) with a similar potentiation, indicating that the potentiation is not caused by inhibition of choline esterase activity. Atropine (10(-6)-10(-5) M) abolishes the response to bombesin plus acetylcholine as well as the response to acetylcholine alone. Tetrodotoxin (10(-6) M) does not block the effect of acetylcholine, bombesin or the combination acetylcholine plus bombesin. Substance P (10(-9)-10(-7) M) which has a similar excitatory effect on the stomach muscle as bombesin, does not potentiate the effect of acetylcholine. Immunohistochemistry has shown the presence of strong bombesin-like immunoreactivity in stomach nerves of the cod and weak bombesin-like immunoreactivity in rainbow trout nerves. In addition, bombesin-like immunoreactivity was demonstrated in endocrine cells in the gastric and intestinal mucosa of both species. It is concluded that bombesin, contained either in nerve fibres or in mucosal endocrine cells, specifically potentiates the effect of acetylcholine in the fish stomach.
在两种硬骨鱼——虹鳟鱼（Oncorhynchus mykiss）和大西洋鳕鱼（Gadus morhua）中，研究了蛙皮素与乙酰胆碱对胃壁平滑肌的相互作用。单独使用乙酰胆碱或蛙皮素对胃肌有兴奋作用。单独使用乙酰胆碱（10⁻⁶ - 10⁻⁵ M）对收缩幅度的影响比蛙皮素（10⁻⁹ - 10⁻⁷ M）大约大10倍。然而，按摩尔计算，蛙皮素比乙酰胆碱更有效。在乙酰胆碱之前0.5 - 3分钟加入蛙皮素（10⁻⁸ - 10⁻⁷ M），以剂量依赖的方式增强乙酰胆碱的作用。这种增强在环行肌制剂中最为明显，但在纵行肌制剂中也存在。蛙皮素以类似的增强作用影响对卡巴胆碱（10⁻⁶ M） 的反应，表明这种增强不是由胆碱酯酶活性的抑制引起的。阿托品（10⁻⁶ - 10⁻⁵ M）消除了对蛙皮素加乙酰胆碱的反应以及对单独乙酰胆碱的反应。河豚毒素（10⁻⁶ M）不阻断乙酰胆碱、蛙皮素或乙酰胆碱加蛙皮素组合的作用。P物质（10⁻⁹ - 10⁻⁷ M）对胃肌的兴奋作用与蛙皮素相似，但不增强乙酰胆碱的作用。免疫组织化学显示，鳕鱼胃神经中有强的蛙皮素样免疫反应性，虹鳟鱼神经中有弱的蛙皮素样免疫反应性。此外，在这两种鱼的胃和肠黏膜的内分泌细胞中也证实有蛙皮素样免疫反应性。得出的结论是存在于神经纤维或黏膜内分泌细胞中的蛙皮素特异性地增强了鱼胃中乙酰胆碱的作用。
