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

This Article Full Text Free Full Text (PDF) Free All Versions of this Article: 100/5/1617    most recent 01277.2005v1 Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal 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 Web of Science (6) Citing Articles via Google Scholar Google Scholar Articles by Aravamudan, B. Articles by Sieck, G. C. Search for Related Content PubMed PubMed Citation Articles by Aravamudan, B. Articles by Sieck, G. C.

Denervation effects on myonuclear domain size of rat diaphragm fibers

Departments of ¹Physiology and Biomedical Engineering, and ²Anesthesiology, Mayo Clinic College of Medicine, Rochester, Minnesota

Submitted 5 October 2005 ; accepted in final form 5 January 2006

Denervation (DNV) of rat diaphragm muscle (DIAm) leads to selective atrophy of type IIx and IIb fibers, whereas the cross-sectional area of type I and IIa fibers remains unchanged or slightly hypertrophied. DIAm DNV also increases satellite cell mitotic activity and myonuclear apoptosis. Similar to other skeletal muscles, DIAm fibers are multinucleated, and each myonucleus regulates the gene products in a finite fiber volume, i.e., myonuclear domain (MND). MND size varies across DIAm fiber types in rank order, I < IIa < IIx < IIb [fiber type based on myosin heavy chain isoform expression]. We hypothesized that, after DNV, the total number of myonuclei per fiber does not change and, accordingly, that MND changes proportionately to the change in fiber size regardless of fiber type. Adult rats underwent unilateral (right side) DIAm DNV, and after 2 wk single fibers were dissected. Fiber cross-sectional area, myonuclear number, and MND were measured by confocal microscopy, and these values in DNV DIAm were compared with those obtained in controls. After DNV, type I fibers hypertrophied, type IIa fiber size was unchanged, and type IIx and IIb fibers atrophied compared with control. The total number of myonuclei per fiber was not affected by DNV. Accordingly, after DNV, type I fiber MND increased by 25%, whereas it decreased in type IIx and IIb fibers by 50 and 70%, respectively. These results suggest that MND is not maintained after DNV-induced DIAm fiber hypertrophy or atrophy. These results are interpreted with respect to consequent effects of DNV on myonuclear transcriptional activity and protein turnover.

respiratory muscles; muscle atrophy; skeletal muscle; fiber type; myosin heavy chain

This article has been cited by other articles:

				L. J. Kirkpatrick, M. Z. Allouh, C. N. Nightingale, H. G. Devon, Z. Yablonka-Reuveni, and B. W.C. Rosser Pax7 Shows Higher Satellite Cell Frequencies and Concentrations Within Intrafusal Fibers of Muscle Spindles J. Histochem. Cytochem., September 1, 2008; 56(9): 831 - 840. [Abstract] [Full Text] [PDF]

				K. Gundersen and J. C. Bruusgaard Nuclear domains during muscle atrophy: nuclei lost or paradigm lost? J. Physiol., June 1, 2008; 586(11): 2675 - 2681. [Abstract] [Full Text] [PDF]

				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]

				Rebuttal from Drs. Esser and McCarthy J Appl Physiol, September 1, 2007; 103(3): 1103 - 1103. [Full Text] [PDF]

				C. Rehfeldt, C. B. Mantilla, G. C. Sieck, R. S. Hikida, F. W. Booth, F. Kadi, S. C. Bodine, and D. A. Lowe In response to Point:Counterpoint: "Satellite cell addition is/is not obligatory for skeletal muscle hypertrophy". J Appl Physiol, September 1, 2007; 103(3): 1104 - 1105. [Full Text] [PDF]