Increased formation of S-nitrothiols and nitrotyrosine in cirrhotic rats during endotoxemia.
Plasma S-nitrosothiols are believed to function as a circulating form of nitric oxide that affects both vascular function and platelet aggregation. However, the formation of circulating S-nitrosothiols in relation to acute and chronic disease is largely unknown. Plasma S-nitrosothiols were measured by chemiluminescence in rats with biliary cirrhosis or controls, and the effect of lipopolysaccharide (LPS) on their formation was determined. Plasma S-nitrosothiols were increased in rats with cirrhosis (206 +/- 59 nM) compared to controls (51 +/- 6 nM, p <.001). Two hours following injection of LPS (0.5 mg/kg) plasma S-nitrosothiols increased to 108 +/- 23 nM in controls (p <.01) and to 1335 +/- 423 nM in cirrhotic rats (p <.001). The plasma clearance and half-life of S-nitrosoalbumin, the predominant circulating S-nitrosothiol, were similar in control and cirrhotic rats, confirming that the increased plasma concentrations were due to increased synthesis. Because reactive nitrogen species, such as peroxynitrite, may cause the formation of S-nitrosothiols in vivo, we determined the levels of nitrotyrosine by gas chromatography/mass spectrometry as an index for these nitrating and nitrosating radicals. Hepatic nitrotyrosine levels were increased at 7.0 +/- 1.2 ng/mg in cirrhotic rats compared to controls (2.0 +/- 0.2 ng/mg, p <.01). Hepatic nitrotyrosine levels increased by 2.3-fold and 1.5-fold in control and cirrhotic rats, respectively, at 2 h following injection of LPS (p <.01). Strong positive staining for nitrotyrosine was shown by immunohistochemistry in all the livers of the rats with cirrhosis. We conclude that there is increased formation of S-nitrosothiols and nitrotyrosine in biliary cirrhosis, and this is markedly upregulated during endotoxemia.
Ottesen
L H
LH
Centre for Hepatology, Royal Free and University College Medical School, Royal Free Campus, University College London, London, UK.
Harry
D
D
Frost
M
M
Davies
S
S
Khan
K
K
Halliwell
B
B
Moore
K
K
D000818:Animals; D019446:Endotoxemia / Q000097:blood* / Q000150:complications; D008401:Gas Chromatography-Mass Spectrometry; D006207:Half-Life; D007150:Immunohistochemistry; D008070:Lipopolysaccharides / Q000008:administration & dosage; D008099:Liver / Q000737:chemistry / Q000378:metabolism / Q000473:pathology; D008103:Liver Cirrhosis / Q000097:blood* / Q000150:complications / Q000378:metabolism; D008163:Luminescent Measurements; D008297:Male; D008657:Metabolic Clearance Rate; D009504:Neutrophils / Q000473:pathology; D009603:Nitroso Compounds; D051381:Rats; D017207:Rats, Sprague-Dawley; D026403:S-Nitrosothiols / Q000097:blood*; D012710:Serum Albumin, Bovine / Q000032:analysis / Q000378:metabolism / Q000493:pharmacokinetics; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000032:analysis / Q000097:blood*
D008070:Lipopolysaccharides; D009603:Nitroso Compounds; D026403:S-Nitrosothiols; C091665:S-nitrosoalbumin; D012710:Serum Albumin, Bovine; C002744:3-nitrotyrosine; D014443:Tyrosine