EFFECT OF MULTIPLE CYTOKINES PLUS BACTERIAL-ENDOTOXIN ON GLUCOSE AND NITRIC-OXIDE PRODUCTION BY CULTURED-HEPATOCYTES

Treatment of cultured hepatocytes with a combination of cytokines, inc luding tumour necrosis factor-alpha, interferon-gamma and interleukin- 1 beta, plus lipopolysaccharide resulted in a time-dependent induction of nitric oxide (NO) synthase (as measured by NO2-+NO3- production) a nd inhibition of hepatic gluconeogenesis and glycogen breakdown. The i nhibition of glucose release was comparable with that observed followi ng treatment of rats with lipopolysaccharide or treatment of isolated hepatocytes with artificial NO donors. In addition, this effect was al so evident with all substrates tested that enter the gluconeogenic pat hway below the level of phosphoenolpyruvate carboxykinase, suggesting that this combination of cytokines may underlie the inhibition of gluc oneogenesis observed in endotoxic shock. The maximal inhibition of glu cose output required the presence of all the cytokines plus lipopolysa ccharide, whereas the induction of NO synthase was independent of the lipopolysaccharide when the cytokines were employed. Inclusion of inte rferon-gamma was essential to obtain a maximal response for either par ameter. Inclusion of 1 mM N-G-monomethyl-L-arginine in the incubation abolished the increase in NO2-+NO3- observed with the complete cytokin e mixture and various combinations; however, it failed to prevent the inhibition in glucose output, indicating that mechanisms other than NO underlie the cytokine-induced inhibition of glucose release.