High-affinity, sodium-dependent gamma-aminobutyric acid uptake by slices of rat ovary.

The high concentration of gamma-aminobutyric acid (GABA) recently demonstrated in rat ovary prompted us to examine the capacity of ovarian slices to take up [3H]GABA. Active uptake, dependent on temperature and sodium concentration, was observed and a kinetic constant (Km) of 1.0 microM found for the uptake process. Ouabain (100 microM) reduced the rate of accumulation of [3H]GABA. Uptake was inhibited only partially by 100 microM d,l-nipecotic acid, but more strongly by 100 microM beta-alanine. These results suggest that the uptake system in ovary possesses properties similar to those of high-affinity GABA transport systems in the brain.