The research outlined in this proposal will examine interactions occurring between ethanol and the metabolic activation of chemical carcinogens. Isolated perfused rat livers will be used for these experiments, because the activation, conjugation and binding of carcinogens to DNA may be studied simultaneously under physiological conditions. This research will be directed at three major objectives. 1) The influence of chronic ethanol administration on the metabolism of benzo(a)pyrene and dimethylnitrosamine in perfused livers and in isolated microsomes will be determined. In these experiments, the nutritional state will also be varied, in order to establish rate-limiting steps for carcinogen activation in whole cells. 2) The influence of the acute addition of ethanol on carcinogen activation will be studied. Direct effects of ethanol on enzymes of mixed-function oxidation and conjugation will be differentiated from indirect effects caused by the metabolism of ethanol and subsequent interactions with other metabolic pathways involved in carcinogen metabolism. 3) The effects of the acute and chronic addition of carcinogens on ethanol metabolism will be assessed by examining enzyme activity as well as the rate of reoxidation of NADH. Potential points of interactions will be determined and the mechanisms involved will be defined. The increased risk of cancer (e.g., of the esophagus, colon, liver) in heavy consumers of ethanol is recongized as a significant health problem. The study of carcinogen activation in intact organs, coupled with measurement of metabolic intermediates and sophisticated optical techniques, such as surface fluorescence of pyridine nucleotides, comprise a unique approach to the study of ethanol-carcinogen interactions. These studies will for the first time define molecular mechanisms by which ethanol may increase the risk of cancer from chemical carcinogens.