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Single-fiber myosin heavy chain polymorphism during postnatal development: modulation by hypothyroidismThe primary objective of this study was to follow the developmental time course of myosin heavy chain (MHC) isoform transitions in single fibers of the rodent plantaris muscle. Hypothyroidism was used in conjunction with single-fiber analyses to better describe a possible linkage between the neonatal and fast type IIB MHC isoforms during development. In contrast to the general concept that developmental MHC isoform transitions give rise to muscle fibers that express only a single MHC isoform, the single-fiber analyses revealed a very high degree of MHC polymorphism throughout postnatal development. In the adult state, MHC polymorphism was so pervasive that the rodent plantaris muscles contained approximately 12-15 different pools of fibers (i.e., fiber types). The degree of polymorphism observed at the single-fiber level made it difficult to determine specific developmental schemes analogous to those observed previously for the rodent soleus muscle. However, hypothyroidism was useful in that it confirmed a possible link between the developmental regulation of the neonatal and fast type IIB MHC isoforms.
Document ID
Document Type
Reprint (Version printed in journal)
di Maso, N. A.
(College of Medicine, University of California Irvine, California 92697, United States)
Caiozzo, V. J.
Baldwin, K. M.
Date Acquired
August 22, 2013
Publication Date
April 1, 2000
Publication Information
Publication: American journal of physiology. Regulatory, integrative and comparative physiology
Volume: 278
Issue: 4
ISSN: 0363-6119
Subject Category
Life Sciences (General)
Funding Number(s)
Distribution Limits
NASA Program Biomedical Research and Countermeasures
NASA Discipline Musculoskeletal
Non-NASA Center
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