In this study, conducted on mice of the C57BL/6J+/+ strain, we investigated the differential effects of
denervation on the isometric contractile properties of the extensor digitorum longus (EDL) and soleus (
SOL) muscles. The contractile properties were studied at 1, 28, 84, and 210 days following unilateral section of the sciatic nerve at 12 weeks of age. When isometric
tetanus tension was expressed relative to wet weight, the denervated
SOL showed an earlier and more pronounced loss in tension generating capacity than the EDL. Both the denervated
SOL and EDL showed potentiation of the twitch tension at 28 days postdenervation. The time to peak twitch tension (
TTP) and the time to half-relaxation (1/2RT) were prolonged by 28 days postdenervation in both muscles. This trend continued to the oldest age-groups studied in the EDL, but reached an apparent plateau in the
SOL at 84 days postdenervation. In response to
fatigue, the denervated
SOL showed a marked decrease in resistance to
fatigue at 1 day but a relatively normal response thereafter, whereas the denervated EDL showed an increase in resistance to
fatigue at and beyond the 28-day period. In spite of the fact that the total contraction time of both muscles increased following
denervation, the predominantly oxidative
SOL remained a slower contracting muscle than the more glycolytic EDL.