Decreased antipyrine clearance following endotoxin administration: in vivo evidence of the role of nitric oxide.
Klebsiella pneumoniae endotoxin has been found to decrease hepatic P450-mediated drug-metabolizing enzyme activity in a time-dependent manner. In this study, we investigated the role of nitric oxide (NO) in the decrease in hepatic drug-metabolizing enzyme activity caused by endotoxin in vivo. We measured in vivo pharmacokinetic parameters of antipyrine in rats treated with endotoxin and/or a selective inhibitor of inducible NO synthase (iNOS), S-methylisothiourea. Intraperitoneal injection of endotoxin (1 mg/kg of body weight) dramatically decreased the systemic clearance of antipyrine, reflecting reduced hepatic drug-metabolizing enzyme activity, and significantly increased the level of nitrite and nitrate (NOx) in the plasma. S-Methylisothiourea (10 mg/kg) reversed this decreasing antipyrine clearance and reduced the level of NOx in plasma. Repeated injections of an NO donor, (+/-)-(E)-4-ethyl-2-[(E)-hydroxyimino]-5-nitro-3-hexenamide (FK-409; 10 mg/kg), at a dose which maintained plasma NOx at the same levels as those caused by endotoxin injection, also decreased the systemic clearance of antipyrine. These findings suggest that the overproduction of NO observed in this animal model is at least partially responsible for the significant reduction in the hepatic drug-metabolizing enzyme activity that may happen in a gram-negative bacterial infection.
Kitaichi
K
K
Department of Medical Technology, Nagoya University School of Health Sciences, Nagoya 461-8673, Japan.
Wang
L
L
Takagi
K
K
Iwase
M
M
Shibata
E
E
Nadai
M
M
Hasegawa
T
T
D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000493:pharmacokinetics*; D000983:Antipyrine / Q000493:pharmacokinetics*; D001711:Biotransformation; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D004731:Endotoxins / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007550:Isothiuronium / Q000031:analogs & derivatives / Q000494:pharmacology; D007711:Klebsiella pneumoniae / Q000378:metabolism*; D008099:Liver / Q000187:drug effects / Q000201:enzymology; D008297:Male; D009569:Nitric Oxide / Q000502:physiology*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D052247:Nitric Oxide Synthase Type II; D009574:Nitro Compounds / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar
D000894:Anti-Inflammatory Agents, Non-Steroidal; D004731:Endotoxins; D004791:Enzyme Inhibitors; D020030:Nitric Oxide Donors; D009574:Nitro Compounds; D007550:Isothiuronium; D009569:Nitric Oxide; D003577:Cytochrome P-450 Enzyme System; C061872:FK 409; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; C027744:S-methylisothiopseudouronium; D000983:Antipyrine