Biological Activity of Synthetic BOMBESIN and Its Related Peptides in the Guinea-pig Gut

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Bombesin tetradecapeptide is extracted from amphibian skin. Synthetic bombesin, its related peptides, and ranatensin-C caused contractile activity in guinea-pig ileum and colon. The contractile patterns were specific and differed from those of ACh and substance-P. Ileum contractile activity required at least the C-terminal octa- or nona-peptide of bombesin. The C-terminal methionine residue was necessary but not sufficient for this effect. Omission of the N-terminal pyroglutamic residue, or extension of the N-terminal length enhanced the effect. The natural site of bombesin action may be other than the gastro-intestinal system. Synthetic bombesin and its analogues did not influence electrically stimulated activity in innervated muscle preparations. Pre- or post treatment by a Ca^<++> -antagonist completely inhibited the contractile activity of bombesin and its analogues. A ganglion blocker, α and β blockers, an antihistaminic and an antiserotonic agent did not affect bombesin's action. Atropine was a weak inhibitor. It is suggested that bombesin acts directly on gut smooth muscle and not through nerves to produce contractility. It also changes membrane permeability to Ca^<++>
東海大学の論文