Expression of the slow myosin heavy chain (MyHC) 2 gene defines slow versus fast avian skeletal muscle fiber types. Fetal, or secondary, skeletal muscle fibers express slow MyHC isoform genes in developmentally regulated patterns within the embryo, and this patterning is at least partly dependent on
Temporal effects of inactivty on myosin heavy chain gene expression in rat slow muscle
β Scribed by Kimberly A. Huey; Roland R. Roy; Kenneth M. Baldwin; V. Reggie Edgerton
- Publisher
- John Wiley and Sons
- Year
- 2001
- Tongue
- English
- Weight
- 331 KB
- Volume
- 24
- Category
- Article
- ISSN
- 0148-639X
- DOI
- 10.1002/mus.1035
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β¦ Synopsis
Abstract
Myosin heavy chain (MHC) mRNA and protein profiles in adult rat soleus and adductor longus were determined after 4, 8, 15, 30, 60, and 90 days of spinal cord isolation (SI). SI results in complete neuromuscular inactivity while leaving the motoneuronβmuscle fiber connections intact. From 15 to 90 days, type I MHC mRNA was significantly decreased, whereas type I MHC protein did not significantly decrease until 30 and 60 days in the soleus and adductor longus, respectively. However, in both muscles, slow MHC downregulation was offset by significant upregulation of the faster MHC isoforms, primarily IIx. From 60 to 90 days, type I MHC was almost completely replaced with faster isoforms at the mRNA and protein levels. Thus, chronic inactivity and unloading of slow rat hindlimb muscles shifted the MHC profile from predominately type I to type IIx MHC mRNA and protein. Β© 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 517β526, 2001
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