Characterization of the receptors responsible for the diphasic effect of bradykinin in rat duodenum

ABSTRACT

The response of the rat duodenum to bradykinin (BK) consists of relaxant and contractile components, which have been atributed to different receptor types. To characterize the receptor responsible for this diphasic response we studied the effects of BK analogues known to act on B1 or B2 receptors in other systems. DesArg**9-Leu**8-BK and Thi**5,**8DPhe**7-BK presented only relaxant and only contractile effects, respectively, whereas DArgOHyp883Thi**5,**8DPhe**7-BK was a potent antagonist of the relaxation (but not of the contraction) induced by BK. Our results show that the relaxant and contractile components of the rat duodenum's response to BK are due to B2 and B1 receptor subtypes, respectively