Fig. 3.

OXPHOS complex enzyme activities. a Complex I. b Complex II. c Complex III. d Complex II + III. e Complex IV. f Complex I + III. Complex I was measured as rotenone-sensitive NADH-decylubiquinone oxidoreductase activity, complex II was measured as succinate decylubiquinone DCPIP reductase activity, complex III was measured as ubiquinone- cytochrome c reductase activity, combined complex II and III was measured as succinate cytochrome c reductase activity, complex IV was measured as cytochrome c oxidase activity, and complex (I + III) was measured as rotenone sensitive NADH-cytochrome c oxidoreductase activity. Activity was expressed as micromole of NADH oxidized/min/milligram protein for complex I; micromole of DCPIP reduced/min/milligram protein for complex II; micromole of cytochrome c reduced/min/milligram protein for complex (I + III), complex (II + III) and complex III; micromole of cytochrome c oxidized/min/milligram protein for complex IV. Values were expressed as mean ± SE of n = 4–6 independent assays. *p < 0.05, statistically different from the normal controls; ^# p < 0.05, statistically different between subpopulations (i.e., IFM vs SSM)