GDNF prevents palmitate-induced suppression of mitochondrial β-oxidation. (A) Mitochondrial respiration profile, (B) basal and maximal mitochondrial respiration, (C) basal and maximal mitochondrial respiration due to exogenous palmitate, (D) ATP production-linked mitochondrial respiration, and (E) proton leak and palmitate-induced uncoupling in HepG2 cells cultured for 6 days in medium containing palmitate (0.1 mM) and supplemented with or without GDNF and during the last 4 days of culture with or without the β3-adrenergic receptor antagonist SR 59230A (10 µM). Oxygen consumption rates (OCR) were assayed in buffer (Assay) with and without GDNF, palmitate and SR 59230A. Plotted are means + SEM (***, P<0.001; **, P<0.01; *, P<0.05. n = 5).