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. Author manuscript; available in PMC: 2012 Mar 15.
Published in final edited form as: Toxicology. 2011 Jan 13;281(1-3):37–47. doi: 10.1016/j.tox.2011.01.001

Fig. 6.

Fig. 6

Representative EPR spectra of BEAS-2B cells showing that MnTBAP does not protect mitochondrial electron transport centers from Cr(VI) treatment. Cells were pre-treated with 0.2 mM MnTBAP (c, d) or vehicle (a, b) for 2 hr, and then 25 µM Cr(VI) was added for 3 hr, after which the cells were washed and harvested as described in the Methods. The final cell suspension (ca. 8 × 106 cells in 0.3 ml HBSS in a 4-mm quartz EPR tube) was immediately frozen in liquid nitrogen. Each sample was analyzed at liquid helium temperature (10 K), and each spectrum was corrected for background. The samples were analyzed using a microwave power of 20 mW (a, c), or 5 mW (b, d). Other instrument settings were: 5 G modulation amplitude, 60 dB receiver gain, 82 msec time constant, 9.633 GHz microwave frequency, modulation frequency = 100 kHz, scan time = 83.9 sec; number of scans, 9.