Stimulatory effects of ethanol on amino acid transport by rat fetal hepatocytes

Abstract

Previous studies have indicated that acute, and especially chronic, maternal ethanol consumption can depress placental uptake of various amino acids. Since the fetal cell itself represents a second barrier to nutrients, one which may be altered by ethanol exposure, the effects of ethanol on amino acid net uptake by rat fetal hepatocytes was addressed. The present study determined that ethanol stimulated amino acid net uptake by fetal hepatocytes grown in monolayer culture. Fetal liver cells were grown in custom Williams' E medium (without L-arginine and with L-ornithine) and exposed to epidermal growth factor (0, 1, 2 or 5 ng per ml) and ethanol (1.7 +/- 0.1 or 3.9 +/- 0.2 mg per ml). Addition of ethanol (3.9 mg per ml) to the culture medium completely blocked measurable cell replication during a 48-hr exposure period. Fetal hepatocytes exposed to ethanol accrued both protein and water in a parallel fashion, both in excess of that by control cells. Ethanol (1.7 and 3.9 mg per ml) for 48 hr stimulated alpha-aminoisobutyric acid net uptake by fetal hepatocytes (p less than 0.05). Efflux was not affected (p greater than 0.05). The onset of this significant stimulation of net uptake was progressive and required in excess of 6 hr of contact with ethanol. This ethanol stimulation of alpha-aminoisobutyric acid net uptake persisted for at least 24 hr following ethanol withdrawal. The component(s) of alpha-aminoisobutyric acid net uptake stimulated by ethanol was independent of extracellular Na+.(ABSTRACT TRUNCATED AT 250 WORDS)