Cell-Specific Effects of Ethanol on Nitric Oxide Synthase Induced by Inflammatory Mediators

To examine the pro- and anti-oxidant properties of nitric oxide (NO) production in alcoholic liver disease, we compared the effects of ethanol pretreatment (24 hrs, 100 mM concentration in a dedicated CO2 incubator) on the induction of inducible NO synthase and its activity in a cell culture system. We employed two types of liver cells as models for the intact liver parenchyma: the rat hepatoma cell FTO2B and rat hepatocytes in primary culture. Cells were incubated with a combination of cytokines (IFN-γ, TNF-α, IL-β) and LPS in the presence or absence of (85 - 93 mM) ethanol in the culture media. At series of time intervals, production of nitric oxide was measured as the accumulation of nitrite and nitrate, using Griess assay. The results revealed that 1) total NO formation was attenuated by ethanol in hepatocytes (ca. 50%) but augmented in FTO2B cells (ca. 37%) and 2) both pretreatment and co-treatment with ethanol were necessary for maximal ethanol effect. These results indicate that the effects of ethanol on inflammatory processes, such as induction of NO synthesis, are cell-type specific.