α1-Syntrophin–deficient mice exhibit impaired muscle force recovery after osmotic shock

Authors


  • This work was supported by grants for Health Science Research; the Center of Excellence (COE) program; the Human Frontier Science Program (HFSP); a Nervous and Mental Disorders grant from the Ministry of Health and Welfare, Japan; Japan Society for the Promotion of Science (JSPS); a grant-in-aid for JSPS fellows; the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan; the Friends of Garrett Cumming Research Fund; the HM Toupin Neurological Science Research Fund; Parent Project Muscular Dystrophy (USA); Canada Foundation for Innovation; Alberta Advanced Education and Technology; University of Alberta; and Muscular Dystrophy Canada.

ABSTRACT

Introduction: α1-syntrophin, a member of the dystrophin complex, recruits membrane molecules, including aquaporin-4, at the sarcolemma. The physiological functions of α1-syntrophin are poorly understood. Methods: We examined the physiological characteristics of α1-syntrophin–deficient muscles under osmotic stress conditions to test the possibility that mutant muscles are less tolerant of osmotic shock. Results: Isolated muscle bundles from mutant mice showed markedly reduced force production after hypo-osmotic shock. In addition, the mutant muscle bundles showed delayed recovery of specific gravity after being exposed to hypo-osmotic conditions. Two consecutive exercise tests on the treadmill revealed their performance in the second test was significantly lower than for wild-type mice. Furthermore, mutant mice had higher serum lactate concentrations after treadmill exercise. Conclusions: Although the lack of α1-syntrophin from the sarcolemma does not lead to muscle degeneration, our results suggest that it may be partly involved in the pathophysiology of dystrophin-deficient Duchenne muscular dystrophy. Muscle Nerve 49: 728–735, 2014

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