CYP2E1 is a cytochrome P450 enzyme thought to be involved in liver toxicity following ethanol (alcohol) consumption. Chlorzoxazone (CZ) is a drug that, in vivo, is metabolized primarily (>95%) by CYP2E1. Several groups have proposed using the rate of CZ metabolism as a marker of CYP2E1 concentrations. During heavy alcohol consumption in rats, CYP2E1 protein concentrations are elevated. In recent studies, it was expected that all alcoholics withdrawn for 24 hr would have elevated rates of CZ metabolism. But, it was found that approximately 20% have CZ metabolism rates in the range of normals. The investigators concluded that some individuals must have noninducible CYP2E1. We believe that their result was due to the fact that, following alcohol administration to rats, CYP2E1 concentrations have been shown to be elevated in the following ways: 1) The presence of alcohol stabilizes the CYP2E1 enzyme and prevents its degradation, increasing the turnover time and increasing CYP2E1 concentrations. When alcohol is eliminated, CYP2E1 is rapidly degraded (half-life of <6 hours) and concentrations return to control values. 2) CYP2E1 mRNA concentrations are increased which results in more CYP2E1 being produced. Disease states or feeding regimens, with or without alcohol, which produce ketoacidosis also induce CYP2E1 through the second mechanism. In this case when alcohol is eliminated, CYP2E1 concentrations remain high and the loss of CYP2E1 is dependent on the rate of loss of CYP2E1 mRNA concentrations. Thus, we believe that the alcoholics with elevated CZ metabolism had elevated CYP2E1 mRNA concentrations and the alcoholics with normal CZ metabolism did not.We will measure CYP2E1 protein and mRNA lymphocyte concentrations (as a marker of liver concentrations). As CZ metabolism might be affected by liver disease a liver biopsy will be performed to make a definitive diagnosis, extra tissue from the biopsy will be used to determine CYP2E1 protein concentrations. Because elevations of CYP2E1 mRNA have been associated with ketonemia, we will also investigate whether the alcoholics have ketonemia at admission or may have had ketonemia very recently. We will measure acetone, b- hydroxybutyrate, acetoacetate, Hemoglobin A1c, insulin and C-peptide concentrations in blood at admission. Subjects will also be asked to complete a food diary for the week preceding admission to the program since behavior such as not eating for 24 h will produce ketonemia. A protocol has been approved. - alcoholic, human, CYP2E1, protein, mRNA, lymphocyte, ketosis, liver, biopsy, chlorzoxazone - Human Subjects
