Synthesis and Degradation of Glucose-6-Phosphate Dehydrogenase in the Rat Uterus

Abstract

Intravenous administration of 5 μg of estradiol or intrauterine application of 5 Mmoles of NADP+ in single or multiple doses increased the level of glucose-6-phosphate dehydrogenase activity (D-glucose-6-phosphate: NADP+ oxidoreductase, EC 1.1.1.49) in the uterus of the ovariectomized mature rat. Enzyme levels were increased 3.5-fold after 36 hr by a single injection of estradiol and 8-fold after 3 days by multiple doses of estradiol. Single or multiple applications of NADP+ resulted in a 2.4-fold increase. During the periods of decreasing enzyme activity following the above 4 treatments, the rate constants of enzyme synthesis (ks) and enzyme degradation (kd) were estimated as described by Segal and Kim (Proc Nat Acad Sci USA 50: 912, 1963). The basal rate of synthesis of glucose-6-phosphate dehydrogenase in the ovariectomized mature rat uterus was 0.0020 units/uterus X hr-1 and the rate of degradation was 0.014 hr-1 (t½ = 50 hr). These values were found to be independent of the treatment used to perturb the resting steady state and represent the average values obtained after all treatments. (Endocrinology89: 1131 1971)