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Early functional muscle regeneration after myotoxic injury in mice is unaffected by nNOS absence

Church, Jarrod, Gehrig, Stefan, Chee, Annabel, Naim, Timur, Trieu, Jennifer, McConell, Glenn and Lynch, Gordon S (2011) Early functional muscle regeneration after myotoxic injury in mice is unaffected by nNOS absence. American Journal of Physiology - Regulatory, Integrative and Comparative Physiology , 301 (5). R1358-R1366. ISSN 0363-6119 (print) 1522-1490 (online)

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Abstract

Nitric oxide (NO) is an important signaling molecule produced in skeletal muscle primarily via the neuronal subtype of NO synthase (NOS1, or nNOS). While many studies have reported NO production to be important in muscle regeneration, none have examined the contribution of nNOS-derived NO to functional muscle regeneration (i.e., restoration of the muscle's ability to produce force) after acute myotoxic injury. In the present study, we tested the hypothesis that genetic deletion of nNOS would impair functional muscle regeneration after myotoxic injury in nNOS−/− mice. We found that nNOS−/− mice had lower body mass, lower muscle mass, and smaller myofiber cross-sectional area and that their tibialis anterior (TA) muscles produced lower absolute tetanic forces than those of wild-type littermate controls but that normalized or specific force was identical between the strains. In addition, muscles from nNOS−/− mice were more resistant to fatigue than those of wild-type littermates (P < 0.05). To determine whether deletion of nNOS affected muscle regeneration, TA muscles from nNOS−/− mice and wild-type littermates were injected with the myotoxin notexin to cause complete fiber degeneration, and muscle structure and function were assessed at 7 and 10 days postinjury. Myofiber cross-sectional area was lower in regenerating nNOS−/− mice than wild-type controls at 7 and 10 days postinjury; however, contrary to our original hypothesis, no difference in force-producing capacity of the TA muscle was evident between the two groups at either time point. Our findings reveal that nNOS is not essential for functional muscle regeneration after acute myotoxic damage.

Item Type: Article
Uncontrolled Keywords: ResPubID24363, skeletal muscle injury, muscle repair neuronal nitric oxide synthase, contraction, fatigue
Subjects: Faculty/School/Research Centre/Department > Institute of Sport, Exercise and Active Living (ISEAL)
FOR Classification > 0606 Physiology
SEO Classification > 9201 Clinical Health (Organs, Diseases and Abnormal Conditions)
Depositing User: VUIR
Date Deposited: 11 Sep 2012 02:04
Last Modified: 23 Mar 2015 05:49
URI: http://vuir.vu.edu.au/id/eprint/9408
DOI: https://doi.org/10.1152/ajpregu.00096.2011
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Citations in Scopus: 9 - View on Scopus

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