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Eccentric contractions do not induce rhabdomyolysis in malignant hyperthermia susceptible mice

¹Muscle Biology Laboratory, Department of Kinesiology and Health, Georgia State University, Atlanta, Georgia; and ²Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas

Submitted 18 July 2008 ; accepted in final form 4 September 2008

Recent studies suggest a link between exercise-induced rhabdomyolysis and mutations of the ryanodine receptor (RYR1) associated with malignant hyperthermia (MH). We hypothesized that MH-susceptible mice (RYR1^Y522S/wt) would exhibit greater anterior crural muscle [tibialis anterior (TA) and extensor digitorum longus (EDL) muscles] damage and strength deficits following the performance of a single or repeated bouts of eccentric contractions compared with wild-type (WT) mice. After a single injury bout, RYR1^Y522S/wt mice produced more isometric torque than WT mice immediately and 3 and 7 days postinjury. Moreover, EDL muscle isometric specific force deficits were fully recovered for RYR1^Y522S/wt but not WT mice 14 days postinjury. The percentage of fibers in TA muscle exhibiting signs of muscle damage 7 and 14 days postinjury were at least three times less in RYR1^Y522S/wt than in WT mice. Uninjured and injured EDL muscle from RYR1^Y522S/wt mice also displayed greater S-glutathionylation of RYR1 than that from WT mice. During the weekly injury bouts, torque production by RYR1^Y522S/wt mice was fully recovered before the third and fourth injury bouts, whereas torque was still reduced for WT mice. Three days after multiple injury bouts, there were 50% fewer fibers exhibiting signs of muscle damage in RYR1^Y522S/wt than in WT TA muscle. These findings indicate that the RYR1^Y522S/wt mutation protects skeletal muscle from exercise-induced muscle injury and do not support a direct association between MH susceptibility and contraction-induced rhabdomyolysis when core temperature is maintained at lower physiological temperatures during exercise.

contraction-induced muscle injury/damage

This article has been cited by other articles:

				J. F. Capacchione and S. M. Muldoon The Relationship Between Exertional Heat Illness, Exertional Rhabdomyolysis, and Malignant Hyperthermia Anesth. Analg., October 1, 2009; 109(4): 1065 - 1069. [Abstract] [Full Text] [PDF]