Autoradiographic assessment of choroid plexus blood flow and glucose utilization in the unanesthetized rat

Choroid plexus blood flow (CPBF) and glucose utilization (CPGU) were measured in two groups, each of seven identically prepared, unanesthetized rats, using complementary quantitative autoradiographic techniques. Both CPBF and CPGU were lowest in the lateral ventricles (0.83 ± 0.01 ml.g^-1.min^-1 and 0.70 ± 0.02 μmoles.g^-1.min^-1, respectively) and highest in the fourth ventricle (1.56 ± 0.05 ml.g^-1.min^-1 and 1.39 ± 0.05 μmoles.g^-1.min^-1, respectively). Despite this heterogeneity, the proportionate relationship between CPBF and CPGU was relatively constant throughout the ventricular system. This suggests that blood flow and metabolism may normally be coupled in the choroid plexus, and that the choroid plexus of the fourth ventricle may account for a disproportionate share of the functional activity of this tissue.