Metabolism of 1-3H-ethanol by isolated liver cells. Time-course of the transfer of tritium from R,S-1-3H-ethanol to lactate and beta-hydroxybutyrate.

Parenchymal cells isolated from the liver of 24 h fasted rats were incubated with 65 mM R,S-1-3H -ethanol plus 3 mM pyruvate as substrates in the absence and presence of 1.7 mM 4-methylpyrazole. Metabolite levels and the time-course of the transfer of tritum from ethanol to lactate and beta-hydroxybutyrate was measured during the first 15 min of ethanol metabolism. The time-course of the loss of tritium from 2-3H-L-lactate and 3-3H-beta-D-hydroxybutyrate in experiments identical to the above-mentioned was estimated. A GLC method for the isolation of lactate and beta-hydroxybutyrate and the preparation of 2-3H-L-lactate and O-3H-beta-D-hydroxybutyrate is described. The incorporation rate of tritium from ethanol into lactate and beta-hydroxybutyrate decreased with time. Addition of 4-methyl-pyrazole decreased the incorporation rate roughly proportional to the decrease in ethanol and acetaldehyde metabolism. The observed incorporation rates of tritium to lactate were corrected for the detritiation rates measured in experiments with I-3H-L-lactate and 3-3H-beta-D-hydroxybutyrate as substrates. The rate of extramitochondrial acetaldehyde oxidation was calculated from the corrected initial rates of incorporation of tritium into lactate to 0-0.4 mumol min-1 (ml of cells)-1.