Acute and chronic ethanol on hepatic oxygen ethanol and lactate metabolism in cats

Abstract

The effects of increasing blood ethanol levels on hepatic hemodynamics and O2, ethanol, and lactate metabolism were studied in two groups of anesthetized cats: a control group and a group whose prior fluid intake contained 2, 4, then 8% ethanol for 24 days. Within each group, responses were compared in cats with acutely denervated and innervated livers. A hepatic venous long-circuit technique with an extracorporeal reservoir was used to allow hemodynamic measurements and repeated sampling of arterial, portal, and hepatic venous blood without depletion of the cats' blood volume. Vmax for ethanol was 105 +/- 9 and 91 +/- 6 mumol.min-1 g liver-1 and Km was 136 +/- 18 and 168 +/- 24 microM for control and chronic alcohol groups, respectively. There was no stimulation of ethanol metabolism after chronic administration. O2 uptake by the liver was not altered during acute ethanol administration in any group and base-line O2 uptakes before acute administration of ethanol were not different between normal and chronic ethanol groups. No evidence for a hypermetabolic state induced by chronic ethanol administration was seen in innervated or acutely denervated livers. Oxidation of ethanol required 40-45% of normal O2 uptake; thus other oxidative processes must have been suppressed during ethanol metabolism. Hepatic lactate uptake remained unaltered when ethanol metabolism was less than 0.5 Vmax, but was suppressed on an equimolar basis with ethanol metabolism when ethanol metabolism rose to greater than 0.5 Vmax. Thus lactate metabolism is one process that can be suppressed to allow ethanol metabolism without additional O2 uptake by the liver.