Simultaneous Determination of Regional Cerebral Blood Flow and Blood—Brain Glucose Transport Kinetics in the Gerbil

Abstract

Cerebral blood flow (CBF) and unidirectional transport of glucose from blood to brain were measured simultaneously in four brain regions of the pentobarbital-anesthetized gerbil. The method consisted of the intravenous injection of a bolus containing [¹⁴C]butanol and [³H]glucose, followed by continuous withdrawal of arterial blood and sampling of brain 25 s later. CBF was lowest in the cerebral cortex (50 ml 100 g⁻¹ min⁻¹), highest in the brainstem (89 ml 100 g⁻¹ min⁻¹), and intermediate in the basal ganglia and cerebellum (66 and 69 ml 100 g⁻¹ min⁻¹, respectively). The kinetics of blood-to-brain glucose transport were measured in animals whose blood glucose concentration had been altered by glucose or insulin injections. The half-saturation constant for glucose transport (K_m) was similar in all brain regions (7.37–8.14 mM), while the maximal rate of transport (V_max) was lowest in the cerebral cortex (1.55 μmol g⁻¹ min⁻¹) and significantly higher in the basal ganglia, cerebellum, and brainstem (1.81–2.02 μmol g⁻¹ min⁻¹). These values for CBF and glucose transport are similar to those reported in the literature for other pentobarbital-anesthetized animals. The method provides a simple and rapid technique for determining the effect of ischemia and alterations in CBF on blood-to-brain glucose transport.