AIM: To investigate the protective effect of isoflurane on energy balance in isolated hepatocytes during in vitro anoxia/reoxygenation, and to compare isoflurane with halothane.METHODS: Hepatocytes freshly isolated from fed rats were suspended in Krebs-Henseleit buffer, and incubated in sealed flasks under O2/CO2 or N2/CO2 (95%/5%, V/V)for 30 or 60 min, followed by 5 or 10 min of reoxygenation,with an added volatile anesthetic or not. ATP, ADP, and adenosine monophosphate in hepatocytes were determined by high performance liquid chromatography, and energy charge was calculated.RESULTS: During 30 min of anoxia, the energy charge and total adenine nucleotide steadily increased with the isoflurane dose from 0 to 2 minimum alveolar anesthetic concentration (MAC), then decreased from 2 to 3 MAC.In short incubations (30-35 min) at 1 MAC isoflurane, energy charge modestly decreased during anoxia, which was partially prevented by isoflurane and completely reversed by reoxygenation, and total adenine nucleotide did not decrease. In long incubations (60-70 min), both energy charge and total adenine nucleotide greatly decreased during anoxia, with partial and no reversal by reoxygenation,respectively. Isoflurane partly prevented decreases in both energy charge and total adenine nucleotide during anoxia and reoxygenation. In addition, 1 MAC isoflurane obviously increased ATP/ADP, which could not be changed by 1MAC halothane.CONCLUSION: Isoflurane partially protects isolated hepatocytes against decreases in both energy charge and total adenine nucleotide during short (reversible) or long (irreversible) anoxia.