Abstract
The mutual interactions and the effects of GABA on the saturable transport components of taurine and hypotaurine were investigated with mouse brain slices. The low-affinity taurine transport was competitively inhibited by both hypotaurine and GABA. Hypotaurine did not alter the kinetic parameters of high-affinity taurine uptake, whereas there occurred some stimulation with GABA, possibly by heteroexchange. Taurine had no significant effects on high-affinity hypotaurine uptake, whereas the low-affinity component was reduced by both taurine and GABA. GABA strongly interfered with the high-affinity hypotaurine uptake, being the preferred substrate in simultaneous uptake experiments. The results confirm that taurine, hypotaurine, and GABA are transported into brain slices by only one two-component system with affinities highest for GABA and lowest for taurine.