ENDOTHELIAL-DERIVED NITRIC-OXIDE PRESERVES ANTICOAGULANT HEPARAN-SULFATE EXPRESSION IN CULTURED PORCINE AORTIC ENDOTHELIAL-CELLS

Nitric oxide (NO) has been shown to inhibit platelet adhesion and aggr egation, but there are no reports on its interaction with the coagulat ion system. We investigated the effect of the L-arginine analogues, N- nitro-L-arginine (LNA), N-G-nitro-L-arginine methyl ester (L-NAME), an d NG-monomethyl-L arginine (L-NMMA), competitive inhibitors of NO prod uction, on endothelial-surface heparan sulfate. Addition of LNA to por cine aortic endothelial cells reduced I-125-labeled antithrombin III b inding to the cell surface heparan sulfate in a dose-and time-dependen t fashion. Significant inhibition was observed with 1 mM LNA, and the maximal suppression (-50% of control) occurred at 10 mM LNA after 12 h , L-NAME (1 mM) and L-NMMA (1 mM) also significantly inhibited the ant ithrombin III binding. The iron chelator desferrioxamine significantly prevented the reduction of antithrombin III binding to LNA-treated ce lls. We further investigated the effect of L-NAME on intracellular oxi dative stress of endothelial cells using a hydroperoxide-sensitive flu orochrome, carboxy-dichloro-dihydrofluorescein diacetate bisacetoxymet hyl ester probe, and revealed that inhibition of NO synthesis by L-NAM E led to a marked increase in intracellular oxidative stress. These re sults demonstrated that the prolonged inhibition of NO synthesis in po rcine aortic endothelial cells decreases the expression of anticoagula nt heparan sulfate on endothelial cells through the increase in intrac ellular oxidative stress, perhaps comprising another mechanism by whic h NO affects the coagulation system in the vasculature. (C) 1997 Elsev ier Science Ireland Ltd.