Nitric oxide synthase inhibitors modulate lipopolysaccharide-induced hepatocyte injury: dissociation between in vivo and in vitro effects.
Effects of endotoxemia-induced NO production on rat liver and hepatocytes in culture were investigated. Rats were treated intraperitoneally with saline, lipopolysaccharide (LPS, 10 mg/kg), L-nitroarginine methyl ester (L-NAME)+LPS, aminoguanidine (AG)+LPS, FK 506+LPS, S-nitroso-N-acetyl penicillamine (SNAP)+L-NAME+LPS and SNAP+FK 506+LPS. Mortality, hepatocyte viability and liver function test were estimated. Liver morphology was observed by light and electron microscopy. Hepatocyte cultures were treated with LPS, cytokine mixture (CM) with or without FK 506, L-NAME or AG. Hepatocyte function and inducible form of NOS (iNOS) expression were evaluated. Twenty-four hours after treatments with saline, LPS, L-NAME+LPS, AG+LPS, FK 506+LPS, SNAP+L-NAME+LPS and SNAP+FK 506+LPS, rat mortalities were 0%, 10%, 48%, 8%, 20%, 38% and 0%, and hepatocyte viabilities were 93+/-3%, 80+/-3%, 52+/-8%, 88+/-1%, 70+/-3%, 80+/-4% and 82+/-3%, respectively. AG+LPS or L-NAME+LPS administration was followed by excessive vacuolization of hepatocytes with lesions in the intermediary lobule zone characterized by features of secondary necrosis as a continuation of apoptotic processes. SNAP+L-NAME+LPS resulted in a well-preserved structure of central vein lobules with sparse signs of apoptosis. Treatment with LPS or CM increased iNOS expression in hepatocyte culture, which was inhibited by L-NAME, FK 506 or AG. AG reduced LPS-induced rise in alanine aminotransferase leakage. LPS-induced NO exerts cytoprotective effects in vivo, while LPS-induced NO in vitro appears to be toxic. Based on the data of this report, one cannot use in vitro results to predict in vivo responses to LPS-induced NO production. The pharmacological modulation of iNOS expression or NO production in vivo or in vitro, therefore, by the development of specific NO donors or inhibitors is promising for improvement of hepatocyte functions under the two experimental conditions, respectively.
Farghali
Hassan
H
Institute of Pharmacology, 1st Faculty of Medicine, Charles University, Albertov 4, 128 00, 2, Prague, Czech Republic. hfarg@lfl.cuni.cz
Canová
Nikolina
N
Kucera
Tomás
T
Martínek
Jindrich
J
Masek
Karel
K
D000410:Alanine Transaminase / Q000097:blood; D000818:Animals; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D006146:Guanidines / Q000494:pharmacology; D022781:Hepatocytes / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D007371:Interferon-gamma / Q000494:pharmacology; D007375:Interleukin-1 / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology / Q000633:toxicity*; D008099:Liver / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors* / Q000235:genetics; D052247:Nitric Oxide Synthase Type II; D009573:Nitrites / Q000032:analysis; D010396:Penicillamine / Q000031:analogs & derivatives* / Q000494:pharmacology; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D016559:Tacrolimus / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D004791:Enzyme Inhibitors; D006146:Guanidines; D007375:Interleukin-1; D008070:Lipopolysaccharides; D009573:Nitrites; D012333:RNA, Messenger; C110881:S-nitro-N-acetylpenicillamine; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; D000410:Alanine Transaminase; D010396:Penicillamine; C004479:pimagedine; D019331:NG-Nitroarginine Methyl Ester; D016559:Tacrolimus