Journal of neurochemistry
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The turnover of cerebrospinal fluid (CSF) glucose was studied in cats during steady-state perfusion. In all experiments, the perfusion fluid contained either tracer [14C]glucose alone or tracer glucose along with 4.45 mM unlabeled glucose. In some studies, serum glucose was lowered with insulin. ⋯ The transport of glucose from serum was independent of the glucose concentration gradient between serum and perfusion fluid. However, when perfusion fluid glucose concentration was greater than that of serum, transport was inhibited. These studies suggest that in maintaining CSF glucose at a lower concentration than serum glucose, with equal amounts of glucose entering and leaving the CSF, 50% of CSF glucose concentration cleared is replaced by 25% of serum glucose concentration.