Crosstalk: phosphorylation of α 1b-adrenoceptors induced through activation of bradykinin B2 receptors

Abstract

The action of bradykinin was studied in rat-1 fibroblasts stably expressing α 1b-adrenoceptors. It was observed that bradykinin and kallidin markedly increase cytosol calcium concentration, but that the B1 agonist, des-Arg 9-bradykinin, only mimicked this effect to a minimal extent. Antagonists, selective for the B2 subtype, such as Hoe 140, blocked this effect of bradykinin and kallidin. Similarly, bradykinin and kallidin stimulated the production of inositol phosphates and B2 antagonists blocked their actions. The possibility that bradykinin could modulate α 1b-adrenoceptors was studied. It was observed that bradykinin and kallidin increased α 1b-adrenoceptor phosphorylation and that such effect was also blocked by Hoe 140. Interestingly, the ability of norepinephrine to increase intracellular calcium concentration was not altered by pretreatment of the cells with bradykinin, i.e. bradykinin induced α 1b-adrenoceptor phosphorylation but this did not lead to receptor desensitization.