Fibrin-derived vasoactive peptides release histamine.

Two fibrin-derived peptides. Ala-Arg-Pro-Ala-Lys and Ser-Gln-Leu-Gln-Lys-Val-Pro-Pro-Glu-Trp-Lys, increase microvascular permeability in rat skin. In the present investigation it is shown that they release histamine from rat mast cells and that their effect on microvascular permeability can be inhibited by previous histamine depletion of the skin or treatment with an antihistamine, the H1-blocker mepyramine maleate. It is concluded that histamine release contributes to the permeability-increasing effect of these peptides as well as of the structurally similar peptides bradykinin, substance P and neurotensin.