Effects of N-acetylcysteine on isolated mouse skeletal muscle: contractile properties, temperature dependence, and metabolism
Abstract The effects of the general antioxidant N-acetylcysteine (NAC) on muscle function and metabolism were examined. Isolated paired mouse extensor digitorum longus muscles were studied in the absence or presence of 20 mM NAC. Muscles were electrically stimulated to perform 100 isometric tetanic contractions (300 ms duration) at frequencies resulting in ∼85 % of maximal force (70–150 Hz at 25– 40 °C). NAC did not significantly affect peak force in the unfatigued state at any temperature but significantly slowed tetanic force development in a temperature-dependent fashion (e.g., time to 50 % of peak tension averaged 35±2 ms [control] and 37±1 ms [NAC] at 25 °C vs. 21±1 ms [control] and 52±6 ms [NAC, P<0.01] at 40 °C). During repeated contractions, NAC maximally enhanced peak force by the fifth tetanus at all temperatures (by ∼30 %).