|
|
||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
1 Endocrinology Research Unit, Mayo Clinic School of Medicine, Rochester, MN, USA
2 General Internal Medicine, Mayo Clinic School of Medicine, Rochester, MN, USA
3 Department of Anesthesiology, Mayo Clinic School of Medicine, Rochester, MN, USA
* To whom correspondence should be addressed. E-mail: short.kevin{at}mayo.edu.
Aging is associated with reduced muscle strength and atrophy of type II muscle fibers. Muscle fiber type and contractile function is primarily determined by myosin heavy chain (MHC) isoforms. There is little 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 y before (N = 77) and after (N = 65) 16 weeks of bicycle training (up to 45 min at 80% peak heart rate, 3-4 d/wk). At baseline MHC I mRNA was unchanged with age, while IIa and IIx declined by 14% and 10% per decade (p < 0.001). MHC IIa and IIx protein declined 3% and 1% per decade with a reciprocal increase in MHC I (p < 0.05). After training, MHC I and IIa mRNA increased 61% and 99%, respectively, and IIx decreased 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 6% and was positively related to age while IIx decreased 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.
This article has been cited by other articles:
![]() |
H. Choi, P.-J. I. Selpides, M. M. Nowell, and B. C. Rourke Functional overload in ground squirrel plantaris muscle fails to induce myosin isoform shifts Am J Physiol Regulatory Integrative Comp Physiol, September 1, 2009; 297(3): R578 - R586. [Abstract] [Full Text] [PDF] |
||||
![]() |
L. Holm, S. Reitelseder, T. G. Pedersen, S. Doessing, S. G. Petersen, A. Flyvbjerg, J. L. Andersen, P. Aagaard, and M. Kjaer Changes in muscle size and MHC composition in response to resistance exercise with heavy and light loading intensity J Appl Physiol, November 1, 2008; 105(5): 1454 - 1461. [Abstract] [Full Text] [PDF] |
||||
![]() |
K. K. Dhatariya, L. J. S. Greenlund, M. L. Bigelow, P. Thapa, A. L. Oberg, G. C. Ford, J. M. Schimke, and K. S. Nair Dehydroepiandrosterone Replacement Therapy in Hypoadrenal Women: Protein Anabolism and Skeletal Muscle Function Mayo Clin. Proc., November 1, 2008; 83(11): 1218 - 1225. [Abstract] [Full Text] [PDF] |
||||
![]() |
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] |
||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
| Visit Other APS Journals Online |