Inhibition of system A amino acid transport activity by ethanol in BeWo choriocarcinoma cells

OBJECTIVE: Our purpose was to investigate the influence of ethanol on system A amino acid transporter in BeWo cells. STUDY DESIGN: BeWo cells were cultured in the absence or presence of ethanol. The function of system A was monitored by the transport of alpha-(methylamino)isobutyric acid. Messenger RNA levels for system A were assessed by Northern analysis. RESULTS: Treatment of BeWo cells with ethanol reduced the activity of system A. The effect was dose and treatment time dependent. The decrease in system A activity was 38% +/- 3% at 0.75% ethanol with a 16-hour treatment time. The activities of several other transporters tested were not affected. The effect on system A activity was associated with a decrease in the maximal velocity of the transport system without affecting the substrate affinity. Ethanol did not alter the messenger RNA levels for system A. CONCLUSION: Exposure of BeWo cells to ethanol significantly reduces the function of system A. This finding has potential implications that may be relevant to the pathogenesis of the fetal alcohol syndrome.