Studies on experimental itch induced by kallikrein and bradykinin

Abstract

Experimental itch, produced by i.c. injection of histamine, bradykinin and kallikrein, was compared in volunteer patients. The latent period until itch was perceived, the duration of the itch and the area of the flare response were measured. The effect of antihistamines on the itch and flare responses was studied. It was found that the latent period was not significantly shorter for bradykinin than for kallikrein, that itch induced by bradykinin but not by kallikrein was inhibited by the antihistamine levomepromazine, and that bradykinin induced a flare reaction which kallikrein did not. It was concluded that bradykinin is not the main final mediator of kallikrein induced itch. Kallikrein is an itch producing proteolytic enzyme which does not release histamine from dermal mast cells.