AMINO ACID TRANSPORT IN BRAIN CORTEX SLICES: I. THE RELATION BETWEEN ENERGY PRODUCTION AND THE GLUCOSE-DEPENDENT TRANSPORT OF GLYCINE

Abstract

Incubation of rat brain cortex slices with glycine in the presence of glucose leads to an accumulation of glycine in the slice. The extent of the accumulation is proportional to the level of adenosine triphosphate in the slice under a wide variety of experimental conditions which lead to changes in this level. Such conditions include change in the glucose concentration in the incubation medium, the presence of metabolic inhibitors, addition of uncoupling agents, alteration of the ionic composition of the medium, incubation under anaerobic conditions, addition of glutamate, X-irradiation, the use of rats of various ages, and the presence of adenosine in the incubation medium. The proportionality is apparent from the constancy of a factor, termed the transport quotient, which is obtained by dividing the extent of uptake of glycine by the observed level of nucleotide pyrophosphate present in the slices.