13C NMR kinetic studies of the rapid stimulation of glucose metabolism by estrogen in immature rat uterus.

Glucose metabolism in control and estrogen stimulated rat uteri was investigated using 13C NMR spectroscopy. By employing an NMR adapted perifusion system, and developing protocols and methods based on the application of [1-13C]glucose labeling, it was possible to measure, with a temporal resolution of 10 min, the kinetics of glucose consumption, lactate production and 13C incorporation into glutamate, alanine and glycogen. In control immature rat uteri, under aerobic conditions, the rates (+/- SEM) of [1-13C]glucose consumption and [3-13C]lactate production were 24 +/- 2 and 7.5 +/- 0.5 mmol/g wet weight/h. The rates of synthesis of [4-13C]glutamate, [3-13C]alanine and 13C labeling of glycogen at C1 of its glucose moieties were significantly lower and were in the range 0.3-0.6 mmol/g wet weight/h. Thus, ca 35% of the labeled glucose was accounted for by the glycolytic and other observed pathways. In vitro stimulation of the uteri by estrogen was found to increase significantly, within 1 h, glucose consumption by 80%, lactate production by 150% and glutamate and glycogen synthesis by 150%, in parallel to a rapid hormonal induction of mRNA for the brain type isozyme of creatine kinase.