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.

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Abstract
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 3H transfer from ethanol to lactate and .beta.-hydroxybutyrate was measured during the first 15 min of ethanol metabolism. The time-course of 3H loss 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 3-3H-.beta.-D-hydroxybutyrate is described. The incorporation rate of 3H from ethanol into lactate and .beta.-hydroxybutyrate decreased with time. Addition of 4-methylpyrazole decreased the incorporation rate roughly proportional to the decrease in ethanol and acetaldehyde metabolism. The observed incorporation rates of 3H to lactate were corrected for the detritiation rates measured in experiments with 2-3H-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 3H into lactate to 0-0.4 .mu.mol min-1 (ml of cells)-1.