Figure 4.

Mn exposures inhibit mitochondrial respiration in primary striatal cultures only at doses coincident with cytotoxicity. A, Relative MTT absorbance following 24-h Mn exposure. Results combined from 3 independent experiments. B, Tetramethylrhodamine methyl ester (TMRM) fluorescence (in arbitrary fluorescence units) following 24-h Mn exposure. Results combined from 3 independent experiments. C, Basal, leak, and maximum mitochondrial oxygen consumption rates (OCR) (pmol/min) per 10⁴ cells. Results combined from 4 independent experiments. Mn concentration (µM) is indicated below respective bars. Concentrations in red reflect concentrations above which significant cytotoxicity is observed. Error bars reflect SEM. *p < .05, **p < .01, ***p < .001, by Dunnett’s test relative to control for each measurement. Abbreviations: MTT, (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide); STR, striatum.