THE INADEQUACY OF SUBSTANCES OF THE "GLUCOSE CYCLE" FOR MAINTENANCE OF NORMAL CORTICAL POTENTIALS DURING HYPOGLYCEMIA PRODUCED BY HEPATECTOMY WITH ABDOMINAL EVISCERATION

Abstract

In a series of rabbits, dogs and cats hypoglycemia was produced by removal of the liver and all of the intra-abdominal viscera by the technique described by Mann. Insulated Ag electrodes were placed in contact with the dura through a trephine opening in the skull. Cortical potentials were recorded by means of a capacity-coupled amplifier and a Grass ink-writing oscillograph. The animals were then allowed to become hypoglycemic and various substances implicated in the "glucose cycle" were injected in order to determine the efficacy in restoring normal cortical activity. Of the substances tested the following were effective: glucose, mannose and maltose. The substances which were ineffective were: fructose, galactose, hexosediphosphate (with or without adenylic acid), glyceric aldehyde, succinate, fumarate, pyruvate and glutamate. Mixtures of some of these substances were also ineffective. Others showed that all of these substances were metabolized by isolated brain tissue. Na malonate failed to cause any inhibitory effect on cortical potentials. The results were not vitiated by alterations in blood pressure. By these methods and the materials used the authors were unable to establish the dependence of cortical function on the oxidation cycle of current theory.