The rate of transport of blood glutamic acid into the brain and the rate of metabolic conversion of the amino acid in the brain were derived by the use of the brain perfution method in vivo and in situ with [D.HC] ·Lglutamic
acid. The net uptake of glutamic acid by the brain was observed. Most of the radioactivity released from the brain into the cerebral venous blood was found to consist of glutamine. Small but significant amounts of output as radioactive GSH and CO2 were also found. Glutamic acid transport and its rate of metabolism were lowered in the glucose. free condition. The size of the compartment of the small glutamic acid pool, which was related closely to the blood glutamic acid, and that of the large glutamic acid pool, which was related closely to the blood glucose, were calculated and compared with each other.</p
