The ratio of NADH to NAD+ fluctuates in response to changes in metabolism. Alcohol metabolism produces a significant increase in the hepatic NADH/NAD+ ratio in the cytoplasm and mitochondria of hepatocytes, as evidenced by changes in the levels of several other molecules in those cell compartments (i.e., an increase in the lactate/pyruvate ratio in the cytoplasm and in the γ-hydroxybutyrate/acetoacetate ratio in the mitochondria) (Cunningham and Bailey 2001). The resulting shift of the redox potential of the hepatocytes causes a marked alteration in various reversible metabolic pathways (Krebs and Veech 1970). As a result, ethanol oxidation vastly increases the availability of oxidizable NADH to the electron transport chain in the mitochondria. NAD+ influences many important cellular reactions.
