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: 99/1/95    most recent 00129.2005v1 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 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 (14) Citing Articles via Google Scholar Google Scholar Articles by Short, K. R. Articles by Nair, K. S. Search for Related Content PubMed PubMed Citation Articles by Short, K. R. Articles by Nair, K. S.

Changes in myosin heavy chain mRNA and protein expression in human skeletal muscle with age and endurance exercise training

Divisions of ¹Endocrinology and ²General Internal Medicine, Department of Internal Medicine, and ³Department of Anesthesiology, Mayo Clinic School of Medicine, Rochester, Minnesota

Submitted 2 February 2005 ; accepted in final form 25 February 2005

Aging is associated with reduced muscle strength and atrophy of type II muscle fibers. Muscle fiber type and contractile function are primarily determined by myosin heavy chain (MHC) isoforms. There are few data available on the effects of aging on MHC isoform expression in humans. In the present study, we tested the hypothesis that MHC isoform protein composition and mRNA abundance would favor a fast-to-slow isoform shift with aging and in response to endurance exercise training. Muscle biopsies were obtained from previously sedentary, healthy men and women, aged 21–87 yr before (n = 77) and after (n = 65) 16 wk of bicycle training (up to 45 min at 80% peak heart rate, 3–4 days/wk). At baseline, MHC I mRNA was unchanged with age, whereas IIa and IIx declined by 14 and 10% per decade, respectively (P < 0.001). MHC IIa and IIx protein declined by 3 and 1% per decade with a reciprocal increase in MHC I (P < 0.05). After training, MHC I and IIa mRNA increased by 61 and 99%, respectively, and IIx decreased by 50% (all P < 0.001). The increase in MHC I mRNA was positively associated with age, whereas the changes in MHC IIa and IIx mRNA were similar across age. MHC I protein increased by 6% and was positively related to age, whereas IIx decreased by 5% and was inversely related to age. These results suggest that the altered expression of MHC isoforms with aging is transcriptionally regulated. In response to endurance exercise, regulation of MHC isoform transcripts remains robust in older muscle, but this did not result in corresponding changes in MHC protein expression.

muscle contractile proteins; gene expression; isokinetic strength; muscle size

This article has been cited by other articles:

				B. A. Parker, S. L. Smithmyer, J. A. Pelberg, A. D. Mishkin, and D. N. Proctor Sex-specific influence of aging on exercising leg blood flow J Appl Physiol, March 1, 2008; 104(3): 655 - 664. [Abstract] [Full Text] [PDF]

				J. M. Gonzalez, J. N. Carter, D. D. Johnson, S. E. Ouellette, and S. E. Johnson Effect of ractopamine-hydrochloride and trenbolone acetate on longissimus muscle fiber area, diameter, and satellite cell numbers in cull beef cows J Anim Sci, August 1, 2007; 85(8): 1893 - 1901. [Abstract] [Full Text] [PDF]

				L. V. Thompson, D. Durand, N. A. Fugere, and D. A. Ferrington Myosin and actin expression and oxidation in aging muscle J Appl Physiol, December 1, 2006; 101(6): 1581 - 1587. [Abstract] [Full Text] [PDF]

				M. T. Korhonen, A. Cristea, M. Alen, K. Hakkinen, S. Sipila, A. Mero, J. T. Viitasalo, L. Larsson, and H. Suominen Aging, muscle fiber type, and contractile function in sprint-trained athletes J Appl Physiol, September 1, 2006; 101(3): 906 - 917. [Abstract] [Full Text] [PDF]

				U. Raue, D. Slivka, B. Jemiolo, C. Hollon, and S. Trappe Myogenic gene expression at rest and after a bout of resistance exercise in young (18-30 yr) and old (80-89 yr) women J Appl Physiol, July 1, 2006; 101(1): 53 - 59. [Abstract] [Full Text] [PDF]