Functional studies of bradykinin receptors in Chinese hamster ovary cells stably expressing the human B-2 bradykinin receptor

Bradykinin B-1 and B-2 receptors, members of the G-protein coupled receptor superfamily, are involved in inflammation and pain, Chinese hamster ovary (CHO) cells stably expressing the human Bz bradykinin receptor (CHO-B-2) we re used to characterize the signal transduction pathways associated with th is receptor and its regulation. The selective B-2 antagonist [H-3]NPC 17731 but not the selective B-1 antagonist [3,4-prolyl-3,4-H-3(N)]-[des-Arg(10), Leu(9)]kallidin ([H-3]DALKD) bound to CHO-B-2 cell membranes with a K-d of 0.77 nM and a B-max of 1087 fmol/mg protein. [H-3]NPC17731 binding was inhi bited by bradykinin ligands in the order: NPC17731 > bradykinin > kallidin > > DALKD > [des-Arg(10)] kallidin (DAKD), consistent with the pharmacologi cal profile of B-2 bradykinin receptors, The B-2 agonist bradykinin and the B-1/B-2 agonist kallidin, but not the B-2 agonist DAKD, increased [S-35]GT P gammaS binding to the CHO-B-2 cell membranes. The Bz bradykinin receptors were co-immunoprecipitated with G alphaq/11. In response to bradykinin sti mulation, coupling of the B-2 receptors to G alphaq/11 was increased by 10- fold. Bradykinin and kallidin, but not DAKD, induced intracellular calcium release in CHO-B-2 cells, which was blocked by NPC17731 but not by DALKD. T hese results demonstrate that B, bradykinin receptors directly coupled to G alphaq/11 to regulate intracellular calcium release, CHO-B-2 cell is a use ful system that can be applied to study the effect of potential agents that may influence the B-2 receptor function. (C) 2001 Elsevier Science B.V. Al l rights reserved.