The effect of severe hypoglycemia upon cerebrospinal fluid formation, ventricular iodide clearance, and brain electrolytes in rabbits.

Severe insulin-induced hypoglycemia in rabbits reduces cerebrospinal fluid (CSF) formation, but not ventricular iodide clearance as measured by ventriculocisternal perfusion. This indicates that CSF production is ultimately glucose-dependent but that ventricular iodide clearance is not. The data suggest that severe hypoglycemia results in intracellular potassium loss within the brain and show that extracellular sodium replaces lost intracellular potassium. Hypoglycemia probably results in cellular adenosine triphosphate (ATP) reduction which affects membrane Na/K ATPase and the ability of the brain cell to maintain a potassium gradient. Potassium levels in the CSF also rise consequent to hypoglycemia. Homeostatic mechanisms that maintain a constant CSF potassium, therefore, are also affected by hypoglycemia.