Measurement of in vivo glucose transport from blood to tissue of experimentally-induced glioma in rat brain.

In experimentally-induced F98 glioma of rat brain, regional blood flow and glucose transfer were assessed by means of double tracer autoradiography to measure Michaelis-Menten constants for the determination of unidirectional glucose transport across the blood-tumor and blood-brain barrier. In brain regions opposite the tumor hemisphere, the maximal glucose transport rate constant, Tm, ranged from 1.41 +/- 0.12 to 3.22 +/- 0.29 mumol/g/min and the half saturation transport constant of glucose, Kt, varied from 2.78 +/- 0.83 to 5.6 +/- 1.94 mumol/ml (estimate +/- standard error of the estimate) yielding a normoglycemic unidirectional glucose inward transport which ranged from 1.24 +/- 0.24 to 1.97 +/- 0.13 mumol/g/min (mean +/- standard deviation). In the tumor periphery, the Tm and the Kt values were 3.64 +/- 0.56 mumol/g/ml and 7.32 +/- 2.12 mumol/min, and in the tumor center, 1.77 +/- 0.25 mumol/ml and 2.76 +/- 1.13 mumol/g/min, respectively. The unidirectional glucose influx of tumor periphery and center in normoglycemia was 1.98 +/- 0.22 and 1.34 +/- 0.16 mumol/g/min, respectively. Despite comparable unidirectional glucose influxes, however, glucose metabolism of tumor tissue located in the periphery (0.83 +/- 0.12 mumol/g/min) and the center (0.41 +/- 0.10 mumol/g/min) of the tumor mass exceeded that of normal gray matter by about 68% and 100% which indicates uncoupling between glucose transport and phosphorylation in experimentally-induced F98 glioma of rat brain.