Skeletal Muscle Response to Endurance Training in IL-6^−/− Mice

Abstract

We examined effects of moderate-intensity endurance training on muscle COX/CS activities and V’O_2max in control WT and IL-6^−/− mice. Animals were exercised for 10 weeks on treadmill for 1 h, 5 days a week at velocity of 6 m·min⁻¹ which was increased by 0.5 m·min⁻¹ every 2 weeks up to 8 m·min⁻¹ . Training triggered an increase of enzyme activities in soleus muscle of WT mice (COX: 480.3±8.9 U·g⁻¹ in sedentary group vs. 773.3±62.6 U·g⁻¹ in trained group, P<0.05 and CS: 374.0±6.0 U·g⁻¹ in sedentary group vs. 534.2±20.5 U·g⁻¹ in trained group, P<0.01, respectively) whereas no changes were observed in soleus of IL6^−/− mice. Moreover, in mixed gastrocnemius muscle of trained IL-6^−/− mice enzyme activities tended to be lower (COX: 410.7±48.4 U·g⁻¹ for sedentary vs. 277.0±36.5 U·g⁻¹ for trained group and CS: 343.8±24.6 U·g⁻¹ for sedentary vs. 251.7±27.1 U·g⁻¹ for trained group). No changes in V’O_2max were observed in WT and IL-6^−/− mice after training. Concluding, moderate-velocity endurance training-induced increase in COX and CS activities in muscles of WT mice only which suggests that IL-6 regulates training-induced skeletal muscle responses to exercise.

Key words

IL-6 knockout - exercise - cytochrome C oxidase activity - citrate synthase activity

• References

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