Estrogenic stimulation of cytidine uptake by the uterus

Abstract

The uptake and distribution of 3H-cytidine by the uterus of the adult ovariectomized rat has been examined during the first 24 hours of estradiol action. There is no increase in uptake during the first 20 minutes. At 2 hours and subsequently tritium uptake into both the acid-soluble and RNA fractions of the uterus is increased, and there is a greater percentage increase in the labeling of acid-soluble 5′-CMP than of RNA. These results probably are the consequence of hormonal regulation of 3H-cytidine entry into the uterus. In ovariectomized controls the rate of nucleoside entry appears to be rate-limiting for phosphorylation. Estradiol increases the rate of cytidine entry sufficiently to allow an intracellular accumulation of the free nucleoside.