Nox4 Is Dispensable for Exercise Induced Muscle Fibre Switch

Introduction By producing H2O2, the NADPH oxidase Nox4 is involved in differentiation of mesenchymal cells. Exercise alters the composition of slow and fast twitch fibres in skeletal. Here we hypothesized that Nox4 contributes to exercise-induced adaptation such as changes in muscle metabolism or muscle fibre specification and studied this in wildtype and Nox4-/mice. Results Exercise, as induced by voluntary running in a running wheel or forced running on a treadmill induced a switch from fast twitch to intermediate fibres. However the induced muscle fibre switch was similar between Nox4-/- and wildtype mice. The same held true for exercise-induced expression of PGC1 alpha or AMPK activation. Both are increased in response to exercise, but with no difference was observed between wildtype and Nox4-/-mice. Conclusion Thus, exercise-induced muscle fibre switch is Nox4-independent.