HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 285/3/R570    most recent 00646.2002v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (25) Citing Articles via Google Scholar Google Scholar Articles by Caiozzo, V. J. Articles by Baldwin, K. M. Search for Related Content PubMed PubMed Citation Articles by Caiozzo, V. J. Articles by Baldwin, K. M.

DEVELOPMENT AND TISSUE PLASTICITY

Single-fiber myosin heavy chain polymorphism: how many patterns and what proportions?

Departments of ¹Orthopaedics, ²Physiology and Biophysics, and ³Otolaryngology, College of Medicine, University of California, Irvine, California 92697

Submitted 21 October 2002 ; accepted in final form 5 May 2003

Previous studies have reported the existence of skeletal muscle fibers that coexpress multiple myosin heavy chain isoforms. These surveys have usually been limited to studying the polymorphic profiles of skeletal muscle fibers from a limited number of muscles (i.e., usually <4). Additionally, few studies have considered the functional implications of polymorphism. Hence, the primary objective of this study was to survey a relatively large number of rat skeletal muscle/muscle regions and muscle fibers (n 5,000) to test the hypothesis that polymorphic fibers represent a larger fraction of the total pool of fibers than do so-called monomorphic fibers, which express only one myosin heavy chain isoform. Additionally, we used Hill's statistical model of the force-velocity relationship to differentiate the functional consequences of single-fiber myosin heavy chain isoform distributions found in these muscles. The results demonstrate that most muscles and regions of rodent skeletal muscles contain large proportions of polymorphic fibers, with the exception of muscles such as the slow soleus muscle and white regions of fast muscles. Several muscles were also found to have polymorphic profiles that are not consistent with the IIIAIIXIIB scheme of muscle plasticity. For instance, it was found that the diaphragm muscle normally contains I/IIX fibers. Functionally, the high degree of polymorphism may 1) represent a strategy for producing a spectrum of contractile properties that far exceeds that simply defined by the presence of four myosin heavy chain isoforms and 2) result in relatively small differences in function as defined by the force-velocity relationship.

isoform; hybrid fiber; polymorphic fiber; force-velocity relationship; fiber type

This article has been cited by other articles:

				C. B. Mantilla, R. V. Sill, B. Aravamudan, W.-Z. Zhan, and G. C. Sieck Developmental effects on myonuclear domain size of rat diaphragm fibers J Appl Physiol, March 1, 2008; 104(3): 787 - 794. [Abstract] [Full Text] [PDF]

				Y.-S. Lee, C.-Y. Lin, V. J. Caiozzo, R. T. Robertson, J. Yu, and V. W. Lin Repair of spinal cord transection and its effects on muscle mass and myosin heavy chain isoform phenotype J Appl Physiol, November 1, 2007; 103(5): 1808 - 1814. [Abstract] [Full Text] [PDF]

				C. E. Pandorf, F. Haddad, A. X. Qin, and K. M. Baldwin IIx myosin heavy chain promoter regulation cannot be characterized in vivo by direct gene transfer Am J Physiol Cell Physiol, October 1, 2007; 293(4): C1338 - C1346. [Abstract] [Full Text] [PDF]

				L. Toniolo, L. Maccatrozzo, M. Patruno, E. Pavan, F. Caliaro, R. Rossi, C. Rinaldi, M. Canepari, C. Reggiani, and F. Mascarello Fiber types in canine muscles: myosin isoform expression and functional characterization Am J Physiol Cell Physiol, May 1, 2007; 292(5): C1915 - C1926. [Abstract] [Full Text] [PDF]

				J. D. Porter, S. Israel, B. Gong, A. P. Merriam, J. Feuerman, S. Khanna, and H. J. Kaminski Distinctive morphological and gene/protein expression signatures during myogenesis in novel cell lines from extraocular and hindlimb muscle Physiol Genomics, February 23, 2006; 24(3): 264 - 275. [Abstract] [Full Text] [PDF]

				H. Zhong, R. R. Roy, B. Siengthai, and V. R. Edgerton Effects of inactivity on fiber size and myonuclear number in rat soleus muscle J Appl Physiol, October 1, 2005; 99(4): 1494 - 1499. [Abstract] [Full Text] [PDF]

				S. Medler, K. J. Brown, E. S. Chang, and D. L. Mykles Eyestalk Ablation Has Little Effect on Actin and Myosin Heavy Chain Gene Expression in Adult Lobster Skeletal Muscles Biol. Bull., April 1, 2005; 208(2): 127 - 137. [Abstract] [Full Text] [PDF]

				E.-K. Pae, J. Wu, D. Nguyen, R. Monti, and R. M. Harper Geniohyoid muscle properties and myosin heavy chain composition are altered after short-term intermittent hypoxic exposure J Appl Physiol, March 1, 2005; 98(3): 889 - 894. [Abstract] [Full Text] [PDF]

				S. Medler, T. Lilley, and D. L. Mykles Fiber polymorphism in skeletal muscles of the American lobster, Homarus americanus: continuum between slow-twitch (S1) and slow-tonic (S2) fibers J. Exp. Biol., July 15, 2004; 207(16): 2755 - 2767. [Abstract] [Full Text] [PDF]