Brain Permeability of Water

Abstract

The equilibration of labeled water (H₂¹⁵O) with the exchangeable water pool of brain was examined during a single capillary transit. The labeled water did not equilibrate freely when cerebral blood flow (CBF) exceeded 20 (ml/100 gm)/min in the rhesus monkey. At normal CBF [.. 50 (ml/100 gm)/min] only 90% of the injected bolus freely equilibrated with brain. This value progressively declined as CBF increased.