EFFECT OF VOLATILE ANESTHETICS ON HYDROGEN PEROXIDE-INDUCED INJURY INAORTIC AND PULMONARY ARTERIAL ENDOTHELIAL-CELLS

Background: Oxidant damage to endothelial cells occurs during inflamma tion and reperfusion after ischemia, mediated in part by endogenously produced hydrogen peroxide (H2O2). Previous studies have established a role for increased cytosolic calcium in the mechanism of endothelial oxidant injury, and have suggested that volatile anesthetics may exace rbate oxidant injury in pulmonary endothelium. However, the effect of volatile anesthetics on oxidant injury to systemic arterial endothelia l cells, and their effect on oxidant-related changes in cytosolic calc ium homeostasis, have not been reported previously. Methods: Primary c ultures of human aortic and pulmonary arterial endothelial cells were studied. The rate of cell death after H2O2 exposure was determined in cell suspension by propidium iodide fluorimetry and lactate dehydrogen ase release. The final extent of cell death 24 h after H2O2 exposure w as determined in monolayer cultures by methyl thiazolyl tetrazolium re duction. Cytosolic calcium and cell. death were determined in single c ells using fura-2 and propidium iodide imaging with digitized, multipa rameter, fluorescent video microscopy.Results: In aortic endothelial c ells, clinical concentrations of halothane (1.0%) and isoflurane (1.5% ) decreased both the rate of cell death and the final extent of cell d eath after H2O2 exposure, with halothane being more protective. Suprac linical concentrations of halothane (2.7%) and isoflurane (4.0%) were less protective. In pulmonary arterial endothelial cells, halothane an d isoflurane had essentially no effect on H2O2-mediated cell death. Th e protective effect of anesthetic in aortic endothelial cells was not due to an enhanced removal of H2O2 by endogenous enzymes. Hydrogen per oxide exposure caused a large increase in cytosolic calcium well befor e cell death, and this was moderated by anesthetic treatment. Conclusi ons: The effect of volatile anesthetics on oxidant injury to endotheli al cells may differ between cells derived from systemic and pulmonary vascular beds. Halothane, and to a lesser extent. Isoflurane, protects against oxidant injury in aortic endothelial cells. The mechanism of protection may involve modulation of the interaction of H2O2 with vita l cellular constituents, and/or amelioration of the toxic increase in cytosolic calcium that follows such interaction.