Ketamine-induced hepatoprotection: The role of heme oxygenase-1

James W. Suliburk, Jeremy L. Ward, Kenneth S. Helmer, Sasha D. Adams, Brian S. Zuckerbraun, David W. Mercer

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


Lipopolysaccharide (LPS) causes hepatic injury that is mediated, in part, by upregulation of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Ketamine has been shown to prevent these effects. Because upregulation of heme oxygenase-1 (HO-1) has hepatoprotective effects, as does carbon monoxide (CO), an end product of the HO-1 catalytic reaction, we examined the effects of HO-1 inhibition on ketamine-induced hepatoprotection and assessed whether CO could attenuate LPS-induced hepatic injury. One group of rats received ketamine (70 mg/kg ip) or saline concurrently with either the HO-1 inhibitor tin protoporphyrin IX (50 μmol/kg ip) or saline. Another group of rats received inhalational CO (250 ppm over 1 h) or room air. All rats were given LPS (20 mg/kg ip) or saline 1 h later and euthanized 5 h after LPS or saline. Liver was collected for iNOS, COX-2, and HO-1 (Western blot), NF-κB and PPAR-γ analysis (EMSA), and iNOS and COX-2 mRNA analysis (RT-PCR). Serum was collected to measure alanine aminotransferase as an index of hepatocellular injury. HO-1 inhibition attenuated ketamine-induced hepatoprotection and downregulation of iNOS and COX-2 protein. CO prevented LPS-induced hepatic injury and upregulation of iNOS and COX-2 proteins. Although CO abolished the ability of LPS to diminish PPAR-γ activity, it enhanced NF-κB activity. These data suggest that the hepatoprotective effects of ketamine are mediated primarily by HO-1 and its end product CO.

Original languageEnglish (US)
Pages (from-to)G1360-G1369
JournalAmerican Journal of Physiology - Gastrointestinal and Liver Physiology
Issue number6
StatePublished - Jun 2009
Externally publishedYes


  • Carbon monoxide
  • Cyclooxygenase-2
  • Inducible nitric oxide synthase
  • Lipopolysaccharide
  • Tin protoporphyrin IX

ASJC Scopus subject areas

  • Physiology
  • Hepatology
  • Gastroenterology
  • Physiology (medical)


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