Subtoxic Mn exposures do not inhibit mitochondrial respiration. (A) STHdh^Q7/Q7 and (B) STHdh^Q111/Q111 basal, leak, and maximum mitochondrial oxygen consumption rates (OCR) (pmol/min) per 10⁴ cells. Mn concentrations (µM), after 24 h exposure, are indicated below the respective bars. Concentrations in red reflect concentrations above which significant cytotoxicity is observed. Results combined from 3 independent experiments, n = 6; total n = 18. Error bars reflect SEM. **p < .01, ***p < .001, by Dunnett’s test relative to control for each measurement.