N(G)-monomethyl-L-arginine inhibits thrombin-stimulated production of cyclic GMP in cultured porcine aortic endothelial cells

Abstract

The production of endothelium-derived nitric oxide evoked by thrombin in cultural porcine aortic endothelial cells was assessed indirectly by changes in cyclic GMP levels. Thrombin stimulated the accumulation of cyclic GMP and, to a lesser extent, of cyclic AMP. The production of cyclic GMP was concentration-dependent and was inhibited by treatment of the cells with hirudin (a selective thrombin inhibitor), methylene blue (an inhibitor of soluble guanylate cyclase) and oxyhaemoglobin (an inactivator of nitric oxide). Treatment of the cells with N(G)-monomethyl-L-arginine (L-NMAA, an inhibitor of the production of endothelium-derived nitric oxide from L-arginine) but not with N(G)-monomethyl-D-arginine (D-NMMA) abolished the production of cyclic GMP evoked by thrombin. These data demonstrate that thrombin stimulates the production of cyclic GMP. This response is presumably due to an enhanced formation of endothelium-derived nitric oxide from L-arginine. Further investigations are needed to determine the role of nitric oxide and cyclic GMP in the responses of endothelial cells to thrombin.