Contribution of bradykinin and nitric oxide to AT₂receptor‐mediated differentiation in PC12 W cells

Abstract

Abstract We investigated the effect of angiotensin II on intracellular cyclic GMP content and neurite outgrowth as an indicator of cell differentiation in PC12 W cells. Neurite outgrowth was examined by phase‐contrast microscopy. Outgrown neurites were classified as small, medium and large, and were expressed as neurites per 100 cells. Angiotensin II (10 −7 m ) increased the outgrowth of medium and large neurites by mean ± SEM 20.2 ± 2.3 and 6.6 ± 1.4 compared with 1.66 ± 0.5 and 0.1 ± 0.06 neurites per 100 cells in control. Cellular cyclic GMP content increased by 50–250% with angiotensin II at concentrations of 10 −6 –10 −4 m . Both blockade of AT 2 receptors and of nitric oxide synthase markedly reduced angiotensin II‐induced neurite outgrowth and cyclic GMP production. In contrast, B 2 receptor blockade had no effect or even increased these angiotensin II effects. Sodium nitroprusside and 8‐bromo‐cyclic GMP both mimicked the effects of angiotensin II on cell differentiation. The protein kinase G inhibitor KT‐5823 inhibited the neurite outgrowth induced by both angiotensin II and 8‐bromo‐cyclic GMP. Our results demonstrate that angiotensin II can stimulate cell differentiation in PC12 W cells by nitric oxide‐related and cyclic GMP‐dependent mechanisms. The effects of angiotensin II on cell differentiation and cyclic GMP production were mediated via the AT 2 receptor and further enhanced by bradykinin B 2 receptor blockade.