Nitric oxide circulates in mammalian plasma primarily as an S-nitroso adduct of serum albumin.

摘要: Abstract We have recently shown that nitric oxide or authentic endothelium-derived relaxing factor generated in a biologic system reacts the presence of specific protein thiols to form S-nitrosoprotein derivatives factor-like properties. The single free cysteine serum albumin, Cys-34, is particularly reactive toward nitrogen oxides (most likely nitrosonium ion) under physiologic conditions, primarily because its anomalously low pK; given abundance plasma, where it accounts for approximately 0.5 mM thiol, we hypothesized this plasma serves as reservoir produced by endothelial cell. To test hypothesis, developed methodology, which involves UV photolytic cleavage S--NO bond before reaction with ozone chemiluminescence detection, measure oxide, S-nitrosothiols, and S-nitrosoproteins systems. We found human contains 7 microM 96% are S-nitrosoproteins, 82% accounted S-nitroso-serum albumin. By contrast, levels only 3-nM range. In rabbits, S-nitrosothiols present at 1 microM; 60 min after administration NG-monomethyl-L-arginine 50 mg/ml, selective potent inhibitor synthetases, decreased 40% (greater than 95% were 80% was albumin); decrease accompanied concomitant increase mean arterial blood pressure 22%. These data suggest naturally circulates complexed S-nitrosothiol species, principal among This abundant, relatively long-lived adduct highly reactive, short-lived can be regulated maintenance vascular tone.