Drug effects on cell metabolism and zebrafish survival. (A) Resazurin metabolism of U2OS cells grown in glucose media(glycolytic conditions) and galactose media (OXPHOS-dependent conditions), after 24 h of treatment with increasing concentration of mitochondrial inhibitors: (i) rotenone – complex I inhibitor, (iiand iii) myxothiazol and antimycin – complex III inhibitors; and (iv) oligomycin – ATP synthase inhibitor; n = 3–4 independent experiments. (B) Resazurin metabolism of U2OS cells in glucose versus galactose media after treatment with MitoPQ and paraquat(left); and their chemical structures (right). Note that the decyl triphenylphosphonium lipophilic cation moiety targets MitoPQ to polarized mitochondria, and that MitoPQ was 100-fold more potent than paraquat in galactose media; n = 3 independent experiments, * P < 0.05. (C) Kaplan-Meier survival analysis of zebrafish larvae exposed to MitoPQ (i), paraquat (ii), or solvent(control), n = 24–50 larvae; and respective median survival times (iii).

Behavioral, functional and biochemical parameters in zebrafish treated with MitoPQ vs. Paraquat. Zebrafish were treated with the indicated concentrations of MitoPQ and paraquat, or solvent (control), from 3 dpf until measurements (at 5 or 6 dpf). (A, B) Sensorimotor reflexes and spontaneous movement at 5 dpf: (Ai) tail and (Aii) head reflexes; (Bi) representative trajectories; (Bii) distance; (Biii) initiations, and (Biv) movement speed; n = 27–78 larvae; *P < 0.05 vs. control. (C) Protein carbonyl groups measured by dot-blot at 5 dpf. n = 3 independent experiments, *P < 0.05 vs. control. (D) Left – energy charge values, calculated with the indicated formula, at 5 dpf (triangles) and 6 dpf (circles); Right – representative HPLC chromatogram with adenine nucleotides; n = 3–4 independent experiments. (E) Heart rate and atrioventricular coordination at 6 dpf; n = 16–19 larvae.