Inability of Cerebrospinal Fluid to Nourish the Spinal Cord

¹ From the Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut, and the Departments of Anatomy and Physiology, School of Medicine, University of California at Los Angeles, Los Angeles, California

Cephalad perfusion with Tyrode's solution of the spinal subarachnoid space between a lumbar and cisternal tap in anesthetized cats had no effect on spinal reflexes, respiration or pupillary size for periods of 8 hours. Alteration of Ca⁺⁺ or K⁺ concentration in the perfusate produced immediate changes in these indices, indicating the availability of the perfusate to neural elements. The onset and course of patellar areflexia, respiratory depression and pupillary dilatation resulting from i.v. insulin-induced hypoglycemia could not be influenced by including high concentrations of glucose, glutamate, succinate or a combination of these latter two in the subarachnoid perfusate. It is concluded that the cerebrospinal fluid cannot act as a sufficient medium for transport from the blood of nutrient substrates essential for maintaining function in the central nervous system.