INFLUENCE OF CHRONIC ALCOHOL INTAKE ON INTESTINAL TAURINE AND ANTIPYRINE TRANSPORT IN PREGNANT RATS

Taurine is a nonessential amino acid that plays a critical role in dev elopment. However, biosynthetic capacity is almost negligible in the f etus and must be supplied by the mother. Therefore, when maternal taur ine status is depressed during gestation, fetal tissue taurine concent rations can also be compromised. In the present study, the effect of c hronic alcohol intake on the intestinal transport of taurine during pr egnancy has been investigated by an in vitro technique that allows mea surement of the unidirectional influx of the amino acid across the int act rat mid jejunum. The influence of alcohol intake on the passive co mponent of the intestinal transport was also investigated with antipyr ine, a model compound for passive diffusion, For chronic alcohol treat ment, the rats were fed a liquid diet containing ethanol (36% of calor ies) or an isocaloric diet (pair-fed control) for 5 weeks before and d uring pregnancy. The animals were sacrificed at 21 days of gestation. Results from the kinetic analysis revealed that chronic ethanol treatm ent significantly decreases the maximum transport (J(m)) of taurine, w ithout modifying the Michaelis-Menten constant (K-m), but enhances its diffusion component (k(a)) compared with that of controls. At the sam e time, this treatment significantly increased the passive diffusion o f antipyrine. These results indicate that although chronic ethanol inh ibits the active transport of taurine, passive diffusion is significan tly increased, However, because of the predominant passive component i n the intestinal absorption of taurine, an overall enhancement in the absorption of this amino acid is observed in alcohol-fed rats. The bio logical and practical implications of our results are discussed.