Rapid steady‐state analysis of blood‐brain glucose transfer in rat

A new kinetic analysis of blood‐brain glucose transport is described, based on a steady‐state model that takes account of cerebral blood flow, mean capillary glucose concentration, and cerebral metabolic rate. The maximal rate (T_max) and half‐saturation constant (K_m) of glucose transport from blood to brain were determined in rats by measuring the rate of blood‐to‐brain glucose transfer at different blood glucose concentrations. Each determination lasted 20 seconds. For whole‐brain, T_max and K_m averaged 258±33 (S.E.) μmol (100 g)^‐1 min^‐1 and 5.9±1.6 (S.E.) mmol 1^‐1, respectively. The regional variations were insignificant. The new approach permits kinetic parameters to be measured locally in brain in rapidly changing functional states.