Fig 5. CoQ (ubiquinone) activity, measured by combined complex activities, among MSTN genotype (CC/II, CT/IN, TT/NN) horses.

NADH cytochrome c oxidoreductase (Complex I + III) (A and C) and Succinate cytochrome c reductase (Complex II + III) (B and D) activities were measured spectrophotometrically on whole skeletal muscle homogenates (A) CC/II: n = 29, CT/IN: n = 28 and TT/NN: n = 7, (B) CC/II: n = 37, CT/IN: n = 32 and TT/NN: n = 11, (C) CC/II: n = 29, CT/IN: n = 28 and TT/NN: n = 7, and (D) CC/II: n = 33, CT/IN: n = 28 and TT/NN: n = 7, all performed in at least duplicate. CI+III (A) and CII+III (B) activities are an indirect measure of CoQ (ubiquinone). CI+III (C) and CII+III (D) activities were measured in the presence of supplementary CoQ₁ (Ubiquinone₁), demonstrating the relative complex activity deficiency is due to lower levels of endogenous CoQ. Results presented with mean ± SEM, p-values where shown indicate significance as measured by a one-way ANOVA with a Bonferroni multiple comparison post-test, * = p ≤ 0.05, ** = p ≤ 0.01, *** = p ≤ 0.001.