Simultaneous measurement of regional blood flow and glucose extraction in rat brain

A method has been described which allows the measurement of cerebral blood flow (CBF) and solute transport across cerebral capillary wall in the same regional sample of rat brain. An inert diffusible indicator (iodoantipyrine) was used to measure a blood flow, in mixed gray and white matter, or approx. 1.0 ml/min/g. Using 3H2O as a reference molecule, the flux of [14C]D-glucose into brain was determined at blood glucose concentration levels between 0.1 and 60 mM. In all discrete areas of brain sampled, a consistent Vmax of 1.92 micromol/min/g and a Km of 8.35 mM was found. Glucose extraction by brain was inversely related to CBF, while a direct relationship was noted for glucose clearance.