IMPORTANCE OF SATELLITE CELLS IN RECOVERY FROM ECCENTRIC CONTRACTION-INDUCED INJURY

Abstract

Eccentric contractions cause injury to skeletal muscle evidenced by prolonged decrements in force. Satellite cells are activated in response to eccentric contraction-induced injury, but their importance in the recovery of force after injury is unknown. PURPOSE To determine if satellite cells are required for the recovery of force after eccentric contraction-induced injury. METHODS Adult female ICR mice were implanted with a stimulating nerve cuff on the common peroneal nerve and assigned to one of four groups: 1) irradiation and eccentric contraction-induced injury (IRR/INJ, n = 11), 2) eccentric contraction-induced injury only (N-IRR/INJ, n = 10), 3) irradiation only (IRR/N-INJ, n = 11), and 4) no intervention (N-IRR/N-INJ, n = 8). Anterior crural muscles were irradiated with a dose of 2500 rad and injured 48 hr later with 150 in vivo maximal eccentric contractions during electrical stimulation. Maximal isometric torque was determined at 0, 7, 14, 21, 28, and 35 days after the induction of injury. Group × time comparisons were made using a two-way ANOVA with repeated measures over time. RESULTS Maximal isometric torque production by N-IRR/INJ mice was not different from control animals by day 28 after injury induction (2.82 ± 0.37 vs. 2.91 ± 0.36 N mm). However, maximal isometric torque production of IRR/INJ animals did not recover and was less than N-IRR/INJ at 14 (19%), 21 (16%), 28 (21%), and 35 (25%) days after injury. CONCLUSION Satellite cells are required for normal force recovery following eccentric contraction-induced injury.