Comparison of Responses to T-Kinin and Bradykinin in the Mesenteric Vascular Bed of the Cat

Champion, H. C., J. A. Santiago, M. A. Czapla, T. J. Bivalacqua, C. Ilgenfritz and P. J. Kadowitz. Comparison of responses to T-kinin and bradykinin in the mesenteric vascular bed of the cat. Peptides 18(9) 1357–1364, 1997.—Responses to T-kinin and bradykinin were compared in the mesenteric vascular bed of the cat. Under constant-flow conditions, injection of T-kinin and bradykinin into the perfusion circuit induced similar dose-related decreases in perfusion pressure. Responses to T-kinin and bradykinin were inhibited by the kinin B 2 receptor antagonist Hoe-140, but were not altered by the B 1 receptor antagonist des-Arg 9-[Leu 8]-BK, the histamine H 1 antagonist pyrilamine, the histamine H 2 receptor antagonist cimetidine, or the H 3 receptor antagonist thioperamide. Vasodilator responses to T-kinin and bradykinin were attenuated by the nitric oxide synthase inhibitor, N ω Nitro- l-arginine methyl ester ( l-NAME), but were not altered by the cyclooxygenase inhibitor, sodium meclofenamate, or the K + ATP channel antagonist, U37883A. These data suggest that vasodilator responses to T-kinin and bradykinin are mediated by kinin B 2 receptor stimulated release of nitric oxide from the endothelium, but that the activation of kinin B 1 receptors, the release of vasodilator prostaglandins, or the opening of K + ATP channels are not involved in the response to T-kinin in the mesenteric vascular bed of the cat.