Spinal fluid formation and glucose influx in normal and experimental hydrocephalic rats

Cerebrospinal fluid (CSF) turnover and glucose influx were measured in normal and kaolin-induced hydrocephalic rats. The CSF formation rate of normal rats was 2.8 microliter/min and after intracisternal kaolin it was reduced to 1.8 microliter/min. The CSF-serum glucose concentration ratio of normal rats was 0.57 and was reduced to 0.47 in hydrocephalic rats. The reduction was associated with a decrease in the net influx of glucose measured in hydrocephalic rats. The fraction of serum glucose transported from blood to CSF in normal and hydrocephalic rats decreased as serum glucose increased above 200 mg/dl. At all serum glucose concentrations studied, the influx of glucose in normal rats was always 2.6 times greater than that in hydrocephalic rats. These results suggest that because the glucose transport mechanism of both groups of rats is only quantitatively different, the number of sites available for glucose transport from blood to CSF is reduced in hydrocephalic rats.