Figure 4. Methyl succinate fails to rescue KB-R7943-inhibited respiration in intact neurons.

(A) Primary rat cortical neurons were control-treated (con, filled squares) or treated with KB-7943 (K-BR, 10 µM, open circles, 20 µM, filled triangles, or 30 µM, open triangles) after three baseline O₂ consumption rate (OCR) measurements (first arrow). Subsequently, oligomycin (oligo, 0.3 µg/ml), FCCP plus pyruvate (F, 2 µM and 10 mM, respectively), and antimycin A (AA, 1 µM) were added as indicated (arrows). (B) Neurons were control-treated (con, filled squares) or treated with KB-7943 (30 µM, all other groups) as in (A). Other additions were as (A) except the FCCP+pyruvate injection after KB-R7943 addition also contained methyl succinate (MeS, 10 mM, open triangles), methyl succinate plus rotenone (10 mM/0.5 µM, MeS/R, open circles), or no additional substrate (open squares). OCRs in (A) and (B) are mean ± SD in triplicate, normalized to the third measurement point and expressed as % baseline OCR.