GLUTAMINE—A MAJOR SUBSTRATE FOR NERVE ENDINGS

Abstract

Abstract— Mammalian cortical synaptosomes incubated in the presence of glucose (2.5 MM) plus glutamine (0.5 mM) showed a 30% increase in transmitter amino acid content over controls with glucose alone and a doubling of glutamate release induced by Veratrine or high K + . Double‐label experiments, i.e. [U‐ 14 C]glucose with [ 3 H]glutamine, and single‐label experiments, i.e. [U‐ 14 C]glucose or [U‐ 14 C]‐glutamine showed that stimulus‐released glutamate was derived principally (80%) from glutamine. Released glutamine‐derived glutamate was of higher (x 2) specific radioactivity than its tissue equivalent. Glutamine alone (0.5–0.75 mM) was much less effective than equivalent amounts of glucose alone, in stimulating respiration and maintaining tissue K + levels.