Influence of Chronic Alcohol Intake on Intestinal Taurine and Antipyrine Transport in Pregnant Rats

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Abstract

Taurine is a nonessential amino acid that plays a critical role in development. However, biosynthetic capacity is almost negligible in the fetus and must be supplied by the mother. Therefore, when maternal taurine status is depressed during gestation, fetal tissue taurine concentrations can also be compromised. In the present study, the effect of chronic alcohol intake on the intestinal transport of taurine during pregnancy has been investigated by an in vitro technique that allows measurement of the unidirectional influx of the amino acid across the intact rat mid jejunum. The influence of alcohol intake on the passive component of the intestinal transport was also investigated with antipyrine, a model compound for passive diffusion. For chronic alcohol treatment, the rats were fed a liquid diet containing ethanol (36% of calories) or an isocaloric diet (pair-fed control) for 5 weeks before and during pregnancy. The animals were sacrificed at 21 days of gestation. Results from the kinetic analysis revealed that chronic ethanol treatment significantly decreases the maximum transport (Jm) of taurine, without modifying the Michaelis-Menten constant (Km), but enhances its diffusion component (ka) compared with that of controls. At the same time, this treatment significantly increased the passive diffusion of antipyrine. These results indicate that although chronic ethanol inhibits the active transport of taurine, passive diffusion is significantly increased. However, because of the predominant passive component in the intestinal absorption of taurine, an overall enhancement in the absorption of this amino acid is observed in alcohol-fed rats. The biological and practical implications of our results are discussed.

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