Figure 4. Absence of MnSOD expression results in increased mitochondrial oxidative stress and alters mitochondrial electron transport chain function.
(A) An increase in mean fluorescent intensity (MFI) of dihydroethidium (DHE) and MitoSOX red staining was detected by flow cytometry in SOD2 knock-out cells (open bars) compared to wild-type cells (closed bars). *P = 0.012 compared to wild-type.
(B) Activities of complex I (left panel) and complex II (right panel) (µmol/min/mg protein) were measured spectrophotometrically. Complex I activity was measured as the rate of rotenone-inhibitable NADH oxidation in the presence or absence of rotenone. Complex II was assayed as the rate of DCIP reduction by Coenzyme Q in the presence and absence of succinate. Activity measurements were normalized to total cellular protein. *P<.05 compared to wild-type.
(C) Increased succinate dehydrogenase activity was detected by histochemical staining in wild-type cells (left panel) compared to knock-out cells (right panel)