Apoptotic insults to human HepG2 cells induced by S-(+)-ketamine occurs through activation of a Bax-mitochondria-caspase protease pathway

S. T. Lee, T. T. Wu, P. Y. Yu, R. M. Chen

Research output: Contribution to journalArticlepeer-review

65 Citations (Scopus)

Abstract

Background. Ketamine is widely used as an i.v. anaesthetic agent and as a drug of abuse. Hepatocytes contribute to the metabolism of endogenous and exogenous substances. This study evaluated the toxic effects of S-(+)-ketamine and possible mechanisms using human hepatoma HepG2 cells as the experimental model. Methods. HepG2 cells were exposed to S-(+)-ketamine. Cell viability and the release of lactate dehydrogenase (LDH) and γ-glutamyl transpeptidase (GPT) were measured to determine the toxicity of S-(+)-ketamine to HepG2 cells. Cell morphology, DNA fragmentation, and apoptotic cells were analysed to evaluate the mechanism of S-(+)-ketamine-induced cell death. Amounts of Bax, an apoptotic protein, and cytochrome c in the cytoplasm or mitochondria were quantified by immunoblotting. Cellular adenosine triphosphate levels were analysed using a bioluminescence assay. Caspases-3, -9, and -6 were measured fluorometrically. Results. Exposure of HepG2 cells to S-(+)-ketamine increased the release of LDH and GPT, but decreased cell viability (all P<0.01). S-(+)-Ketamine time-dependently caused shrinkage of HepG2 cells. Exposure to S-(+)-ketamine led to significant DNA fragmentation and cell apoptosis (P=0.003 and 0.002). S-(+)-Ketamine increased translocation of Bax from the cytoplasm to mitochondria, but decreased the mitochondrial membrane potential and cellular adenosine triphosphate levels (all P<0.01). Sequentially, cytosolic cytochrome c levels and activities of caspases-9, -3, and -6 were augmented after S-(+)-ketamine administration (all P<0.001). Z-VEID-FMK, an inhibitor of caspase-6, alleviated the S-(+)-ketamine-induced augmentation of caspase-6 activity, DNA fragmentation, and cell apoptosis (all P<0.001). Conclusions. This study shows that S-(+)-ketamine can induce apoptotic insults to human HepG2 cells via a Bax-mitochondria-caspase protease pathway. Thus, we suggest that S-(+)-ketamine at a clinically relevant or an abused concentration may induce liver dysfunction possibly due to its toxicity to hepatocytes.

Original languageEnglish
Pages (from-to)80-89
Number of pages10
JournalBritish Journal of Anaesthesia
Volume102
Issue number1
DOIs
Publication statusPublished - Jan 2009

Keywords

  • Anaesthetics i.v., ketamine
  • Liver, hepatotoxicity
  • Metabolism, ATP, DNA
  • Theories of anaesthetic action, cellular mechanisms

ASJC Scopus subject areas

  • Anesthesiology and Pain Medicine

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