Effect of bradykinin on cultured bovine corneal endothelial cells

To clarify the effect of bradykinin on cytosolic free calcium mobilization and cell proliferation in cultured bovine corneal endothelial cells (BCEC), Methods: The cytosolic free calcium concentration (Ca2+](i))) was measured with the InCa (TM) Imaging System after the treatment of bradykinin (10(-1 1) to 10(-7) M) alone or with the pretreatments of EGTA, bradykinin recepto r (Bk-1 and Bk-2) antagonists and an inhibition of phospholipase C (U-73122 ). Also, the effect of bradykinin on cell proliferation in BCEC was evaluat ed using cell counts, Results: In BCEC, [Ca2+](i) in the resting state was 87 +/- 9 nM. Bradykinin induced an increment of [Ca2+](i) in a concentratio n-dependent manner and its 50% effective concentration was approximately 5 x 10(-11) M. A [Ca2+](i) increment at 10(-8) Mbradykinin was inhibited with the pretreatment of EGTA, an extracellular calcium chelator, U-73122 (5 x 10(-6) M) attenuated the bradykinin-induced [Ca2+](i) increment. The pretre atment of HOE-140 (Bk2 antagonist) almost attenuated the bradykinin (10(-8) M)-induced [Ca2+](i) increase, but des-Arg(9)-[Leu(8)]-bradykinin (Bk-1 an tagonist) did not suppress it. To investigate the physiological effect of b radykinin, the effect of bradykinin on cell proliferation was studied. 10(- 8) M of bradykinin produced a significant increase in cell numbers. This mi togenic effect of bradykinin was inhibited by the Bk-2 antagonist. Conclusi ons: Bradykinin-induced stimulation of the signal transduction pathway in B CEC is coupled with the Bk-2 type receptor, Furthermore, bradykinin produce s the mitogenic effect in BCEC, Copyright (C) 2001 S.KargerAG, Basel.