The hepatotoxicities of endotoxin and ethanol: Comparisons in vitro using the precesion-cut rat liver slice model

Using the precision-cut rat liver slice model, the in vitro toxicities of endotoxin and ethanol, independently and in combination, were evaluated. Hepatotoxicity was assessed by two measures: the leakage of LDH from slice to medium and the ability of slices to reduce a tetrazolium compound, MTT. Ethanol, in concentrations of 1% and greater, exhibited a time and dose dependent hepatotoxicity; MTT reductive capacity was more profoundly affected than LDH leakage. Endotoxin (0.1 to 100 μg/ml), however, had only a modest effect on MTT reduction and did not perturb LDH leakage. When combined in vitro, the toxicities of 2% ethanol and various concentrations of endotoxin were additive. Slices prepared from the livers of rats injected ip with endotoxin one day previously sustained considerably more injury (compared to normal rat liver slices) upon subsequent in vitro exposure to either endotoxin or ethanol. Prior in vivo exposure to ethanol, however, did not affect the subsequent in vitro toxicity of endotoxin. Thus, while endotoxin exhibits only subtle toxic effects upon liver slices in vitro, exposure to endotoxin in vivo renders the liver more susceptible to subsequent direct injury by endotoxin or ethanol.