Spasmogenic activity of chemotactic N-formylated oligopeptides: identity of structure--function relationships for chemotactic and spasmogenic activities.

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Abstract
The chemotactic N-formylated oligopeptides are potent spasmogenic agents for guinea pig ileum. Structure-activity studies with various N-formylated peptides suggest that presence of a specific receptor that resembles in specificity the formyl peptide receptor on leukocytes. A competitive antagonist of the formyl peptide receptor on leukocytes also inhibited formyl peptide-induced ileum contraction, while the antihistamine diphenhydramine was without effect. The contractile response caused by the synthetic N-formylated peptides differed from those induced by acetylcholine, histamine and substance P. A latent period after treatment with the N-formyl peptides was seen before the onset of the response, and a sustained contractile response was not maintained. Tachyphylaxis occurred, but complete recovery of activity was seen after a 20- to 30-min rest period. Broad biological roles of prokaryotic signal peptides from bacteria as acute inflammatory mediators were suggested.