TABLE 3.

Antioxidant Status (Total Antioxidant Capacity) 4 h and 24 h after 10 Gy Irradiation of MnSOD^tet/tet Cells

Cell line	Trolox units per mg protein
	0 Gy	4 h after 10 Gy	24 h after 10 Gy
MnSOD−/−	0.106 ± 0.001	0.046 ± 0.001	0.159 ± 0.013
		P3 = 0.0003	P3 = 0.1196
MnSOD−/− + doxy	0.119 ± 0.008	0.045 ± 0.001	0.222 ± 0.042
	P2 = 0.2403	P3 = 0.0147	P3 = 0.1075
MnSODtet/+	0.181 ± 0.015	0.096 ± 0.001	0.175 ± 0.083
	P1 = 0.0379	P3 = 0.0299	P3 = 0.9532
MnSODtet/+ + doxy	0.151 ± 0.015	0.083 ± 0.007	0.243 ± 0.093
	P2 = 0.2929	P3 = 0.0450	P3 = 0.6168
MnSODtet/tet	0.158 ± 0.002	0.087 ± 0.013	0.199 ± 0.044
	P1 = 0.0018	P3 = 0.0308	P3 = 0.5250
MnSODtet/tet + doxy	0.259 ± 0.033	0.123 ± 0.003	0.406 ± 0.049
	P2 = 0.0276	P3 = 0.0125	P3 = 0.2929
MnSOD−/−	0.130 ± 0.001	0.047 ± 0.002	0.159 ± 0.090
	P1 = 0.0035	P3= 0.0011	P3 = 0.1940
MnSOD−/− + doxy	0.126 ± 0.005	0.071 ± 0.001	0.141 ± 0.063
	P2 = 0.5149	P3 = 0.0087	P3 = 0.2346

Notes. Cells from the MnSOD^+/+, MnSOD^tet/tet, MnSOD^tet/+ and MnSOD^−/− cell lines were grown in the presence or absence of 0.25 μg/ml doxycycline for 24 h and then were irradiated to 10 Gy. At three times (immediately after irradiation, 4 h and 24 h later), cells were harvested for assay of total antioxidant capacity. Antioxidant levels are expressed as trolox units/mg protein. Results are shown for the 4 and 24 h times. P1 is the P value comparing either MnSOD^tet/+, MnSOD^tet/tet or MnSOD^−/− cells at 0 Gy to the MnSOD^+/+ cell lines. P2 is the P value which compares each cell line to itself grown in the presence or absence of doxycycline. P3 compares each cell line grown under the same conditions (doxy or none) at 10 Gy with 0 Gy. Significant P values are italicized.