Biochimica Et Biophysica Acta Bba 75059 T H E Effect of Estrogen on Sugar Transport in T H E Rat Uterus

I. The characteristics of sugar transport in the isolated rat uterus were studied using the non-metabolized glucose analogue 3-0-methyl-D-glucose. The effect of estrogen injection into ovariectomized rats on the transport rate was also determined. 2. Estrogen injection increased the initial rate of 3-0-methylglucose transport into uterine cells. The effect was evident at 2 h, and maximal at 4 h. After 12 h the control value was attained again. 3. Sugar transport obeyed Michaelis-Menten kinetics. Estrogen increased the Vmax 2-fold, but did not change the Kin. 4. Sugar transport exhibited substrate specificity, competition between sugar pairs, and countertransport. 5. Estrogen increased the rate of sugar effiux from the uterus. 6. Estradiol, insulin, N-ethylmaleimide, NaCN, diisopropylphosphorofluoridate, p-chloromercuribenzoate and dinitrophenol did not alter the transport rate when added in vitro. 7. It is concluded that estrogen increases the rate of sugar transport in the rat uterus and that sugar transport takes place by means of a specific mobile carrier transport system.