Kinetics of ethanol metabolism in the intact rat and monkey

Because ethanol distributes evenly throughout body water and because it can be given in saturating doses, it offers an opportunity for a comparison of kinetic studies in vivo with those performed in vitro. Ethanol was given intraperitoneally to rats and monkeys in a dose (1 g/kg) which not only saturated the enzyme system responsible for its oxidation, but which permitted sufficient time for its even distribution throughout body water before metabolism reduced its concentration to a level where its oxidation proceeded in accordance with first order kinetics. Blood alcohol concentrations were determined at intervals and these data were used to calculate apparent kinetic constants in vivo for the oxidation of ethanol. The apparent Michaelis constants in vivo obtained in this manner compared quite favorably with those for the reaction of ethanol with crude alcohol dehydrogenase preparations obtained from the livers of the same species. The calculated apparent maximum velocities in vivo were quite similar to the observed maximum rates in vivo of ethanol metabolism seen in each of the species. Kinetic data were more closely correlative in the rat than in the monkey.