Effect of a brief hypoxic/hypotensive episode on the in vivo release of cerebral cortical gamma-aminobutyric acid and glycine.

gamma-Aminobutyric acid (GABA) and glycine levels in rat cerebral cortical superfusates rose during a 10-min period to reach stable concentrations of approximately 0.55 microM and approximately 12.3 microM, respectively. In cerebrospinal fluid withdrawn from the fourth ventricle, the GABA concentration was 0.1 microM, and that of glycine, 10.55 microM. GABA, and to a lesser extent glycine, concentrations increased in the cortical superfusates during and immediately following exposure of the rats to a 5-min period of 5% oxygen in nitrogen inhalation.