In Vitro Studies of Glucose Metabolism in Human Epidermal Keratinocytes Exposed to Sulfur Mustard

Abstract

The mechanism of metabolic injury induced by the chemical warfare agent sulfur mustard (2,2'-dichlorodiethyl sulfide, HD) was examined in cultured human epidermal keratinocytes (HEK). Although the cell viability and oxidized nicotinamide-adenine dinucleotide phosphate (NADP + ) levels were maintained for 8 h after exposure to 0.33 mM HD, glucose utilization and lactate production were inhibited by 50%. The oxidized nicotinamide-adenine dinucleotide (NAD + ) content decreased linearly during the initial 3 to 4 h, leveling off to between 50 and 60% of control values for ≤8 h. Exposure to HD at 0.07 mM HD caused a time-dependent decrease in these same parameters. At 0 to 8 h after exposure, concentrations of HD between 0.03 and 0.17 mM caused increased rates of glycolysis in half of the experiments, thus suggesting activation of energy-requiring repair pathways. These results demonstrate that depletion of NAD + and inhibition of glucose metabolism are a function of HD dose and postexposure time. NAD + depletion and inhibition of glucose metabolism preceded the loss of cell viability as determined by dye exclusion. The various end points measured showed similar, but not necessarily identical, responses to the dose of HD and the time after exposure. HD also induced shifts in the cellular metabolic patterns; this suggests that the alterations in glucose metabolism were not simply a function of NAD + depletion. The data are consistent with the conclusion that HEK metabolize glucose primarily via anaerobic glycolysis and that HD induces complex shifts in the patterns of metabolic activity. We conclude that the relationships between HD exposure, intarcellular NAD + , and the rates of glucose metabolism are more complex than originally proposed.