Properties of estrogen-sensitive uterine sugar metabolism specificity of inhibitory sugars.

Abstract

The in vitro uterine metabolism of glucose-U-14C was examined by determining 14CO2 production and the incorporation of glucose carbons into lipid and protein. Sugar transport and phosphorylation were investigated by measuring the uterine conversion of 2-deoxyglucose- l-14C to 2-deoxyglucose-6-PO4-l-14C. The presence of certain unlabeled sugars in the incubation medium caused inhibition of glucose metabolism, while equimolar quantities of other sugars were not inhibitory. Inhibition was concentration dependent and was exhibited by sugars which are phosphorylated in a manner analogous to glucose. Although several nonmetabolized sugars are not inhibitory, 2-deoxyglucose, which is only transported and phosphorylated, does display considerable inhibition of glucose metabolism. Similarly, glucose and mannose are quite effective in inhibiting 2-deoxyglucose transport and phosphorylation. These findings support the hypothesis that a rate-determining, phosphorylation-dependent entry step governs uterine sugar meta...