Figure 2.

Effect of various compounds on ALA and GABA uptake. Washed cells were preincubated for 15 min with each compound in PBS-0.1% glucose. Then 0.1 mM ¹⁴C-ALA (A) or 0.1 mM ¹⁴C-GABA (B) was added and radioactivity was measured after 30 min. The final concentration of all compounds assayed was 10 mM, except ALA methyl ester and levulinic acid which were 1.25 mM and 3.3 mM, respectively. Values are expressed as percentage of inhibition relative to the control uptake without competitor.