Figure 3.

Muscle function in mKO mice. A) Maximum isometric specific force (N/cm²), normalized by total fiber CSA, for GTN muscles from control mice (solid bars) and mKO mice (shaded bars) at 6–8 mo of age (n=5). *P < 0.05 vs. WT control. B) Force generated during direct muscle stimulation and nerve stimulation for GTN muscles of control (solid black), mKO (shaded bars), and Sod1^−/− (open bars) mice. C) Rota-rod performance in control mice and mKO mice at 6–8 mo of age was measured for 3 consecutive days, with 4 trials/d. Data represent average ± se time (s) that mice remain on the rotating rod before falling off. D) Treadmill performance test. Data from the treadmill performance test show no difference in the duration of time that control (WT, n=6) and mKO (n=5) mice were able to run. E) Force production during a series of repeated isometric contractions, expressed as a percentage of the initial force. Lines represent the average response of 4 muscles form 6- to 8-mo-old mice. Although mKO mice showed a tendency to lose force faster, the data are not significantly different between WT and mKO mice.