Ethanol treatment selectively decreases neutral amino acid transport in cultured hepatocytes

Primary cultures of adult rat hepatocytes were used to study the effects of 100 mM ethanol on various neutral amino acid transport systems. Ethanol exposure for 24 h selectively decreased amino acid uptake by the A and N systems by 40-70%, but had no significant effect on the ASC and L systems. The decrease in the A system was significant after 3 h of ethanol exposure, and the activity was not affected by the presence or absence of ethanol during the uptake measurements. Kinetic analysis showed that ethanol treatment affected predominantly the high-affinity component of A system activity by decreasing the apparent Vmax without significantly changing the apparent Km. Ethanol treatment did not prevent the cells from increasing A system activity in response to insulin and glucagon, but the magnitude of hormone-stimulated uptake was reduced.