BRADYKININ RECEPTORS IN INTESTINAL SMOOTH MUSCLES AND THEIR POSTRECEPTOR EVENTS RELATED TO CALCIUM

THE effects of trifluoperazine and verapamil on bradykinin- and des-Ar g9-bradykinin induced responses of isolated rat duodenum and guinea-pi g ileum were investigated to elucidate post-bradykinin receptor events . Verapamil and trifluoperazine inhibited bradykinin induced relaxatio ns and contractions and des-Arg9-bradykinin induced contractions in ra t duodenum. Bradykinin induced contractions of ileum were also inhibit ed by trifluoperazine and verapamil. Since non-competitive affinity co nstants of trifluoperazine and verapamil for the relaxant responses to bradykinin in duodenum and for the contractile responses to bradykini n in ileum are different, post-bradykinin receptor events related to c alcium may be different in ileum and duodenum. In addition, affinity c onstants of bradykinin in guinea-pig ileum and rat duodenum are also d isparate suggesting the presence of different types of bradykinin B2 r eceptors in these two organs.