Kinin receptors in experimental inflammation

Abstract

The contractile response of the rat isolated urinary bladder to kinins is mediated by receptors of the B1 and of the B2 types, as this preparation responds to des-Arg9-bradykinin (des-Arg9-BK), a fairly selective stimulant of receptor B1 and to [Tyr(Me)8]-BK, a potent agonist on receptor B2. Des-Arg10-[Leu9]-kallidin, a specific and competitive antagonist of the action of kinins on receptor B1, has been found to block the effect of des-Arg9-BK in concentrations similar to those required in the rabbit aorta; therefore, the B1 receptor of the rat urinary bladder is analogous to that of the rabbit vascular tissue.The response of the rat urinary bladder to des-Arg9-BK increases progressively from near null level during the incubation in vitro and can be abolished by cycloheximide; this suggests that receptor B1 of the rat urinary bladder is formed de novo.The inflammation of the bladder induced by intravesical injection of the detergent Triton X-100 enhances the initial response to des-Arg9-BK without modifying the response to other agents. The B1 receptor is formed in vivo in the rat urinary bladder submitted to the Triton X-100 treatment but not in the control untreated organ. The local de novo synthesis of B1 receptors for kinins that follows a noxious stimulus is proposed as a possible mechanism implicated in the chemical mediation of the inflammatory process.