| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
|
|
|
|||||||
|
|||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
1 Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, USA; Center on Aging, University of Minnesota, Minneapolis, MN, USA
2 Department of Physical Therapy, Georgia State University, Atlanta, GA, USA
3 Center on Aging, University of Minnesota, Minneapolis, MN, USA; School of Kinesiology, University of Minnesota, Minneapolis, MN, USA
4 Center on Aging, University of Minnesota, Minneapolis, MN, USA; Department of Physical Medicine and Rehabilitation, University of Minnesota, Minneapolis, MN, USA
* To whom correspondence should be addressed. E-mail: dl{at}ddt.biochem.umn.edu.
The study's purpose was to determine whether increased muscle activity could reverse myosin structural alterations that occur in aged rat muscle and whether those alterations could be induced in young rat muscle by decreased activity. Semimembranosus muscle activity was increased by electrical stimulation (200 ms trains, 154 Hz, 5 V) through a nerve cuff on the tibial branch of the ischiatic nerve. The protocol consisted of 5 sets of 6-10 maximal isometric contractions performed twice per wk for 4 or 8-10 wk. Decreased muscle activity was induced by denervation of the semimembranosus muscle for 2 or 4 wk. Semimembranosus fibers were then studied for Ca2+-activated force generation. Fibers were also spin-labeled on the myosin catalytic domain and studied using electron paramagnetic resonance (EPR) spectroscopy to assess myosin structural distribution. Four and 8-10 wk of increased muscle activity in rats aged ~32 mo resulted in -16 and +4 % changes in specific tension, respectively (p< 0.01). EPR spectra showed that the fraction of myosin heads in the strong-binding structural state during contraction was reduced at 4 wk (0.241 ± 0.020 vs. 0.269 ± 0.018; p=0.046) but returned to normal by 8-10 wk (p=0.67). Two and 4 wk of decreased muscle activity in ~9 mo-old rats resulted in 23 and 34% reductions, respectively, in specific tension; EPR spectra showed 16 and 35% decreases in strong-binding myosin (p<0.01). These data support the hypothesis that changes in muscle activity affect muscle strength, at least in part, through alterations in myosin structure and function.
This article has been cited by other articles:
|
|
 |
|
  J. Feng, H. Xie, D. L. Meany, L. V. Thompson, E. A. Arriaga, and T. J. Griffin Quantitative Proteomic Profiling of Muscle Type-Dependent and Age-Dependent Protein Carbonylation in Rat Skeletal Muscle Mitochondria J. Gerontol. A Biol. Sci. Med. Sci., November 1, 2008; 63(11): 1137 - 1152. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. L. Moran, S. A. Nelson, R. M. Landisch, G. L. Warren, and D. A. Lowe Estradiol replacement reverses ovariectomy-induced muscle contractile and myosin dysfunction in mature female mice J Appl Physiol, April 1, 2007; 102(4): 1387 - 1393. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Trappe, M. Harber, A. Creer, P. Gallagher, D. Slivka, K. Minchev, and D. Whitsett Single muscle fiber adaptations with marathon training J Appl Physiol, September 1, 2006; 101(3): 721 - 727. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Zhong, D. A. Lowe, and L. V. Thompson Effects of hindlimb unweighting and aging on rat semimembranosus muscle and myosin J Appl Physiol, September 1, 2006; 101(3): 873 - 880. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
N. A. Fugere, D. A. Ferrington, and L. V. Thompson Protein nitration with aging in the rat semimembranosus and soleus muscles. J. Gerontol. A Biol. Sci. Med. Sci., August 1, 2006; 61(8): 806 - 812. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. L. Moran, G. L. Warren, and D. A. Lowe Removal of ovarian hormones from mature mice detrimentally affects muscle contractile function and myosin structural distribution J Appl Physiol, February 1, 2006; 100(2): 548 - 559. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. Szentesi, M. A. Bekedam, B. J. van Beek-Harmsen, W. J. van der Laarse, R. Zaremba, A. Boonstra, F. C. Visser, and G. J. M. Stienen Depression of force production and ATPase activity in different types of human skeletal muscle fibers from patients with chronic heart failure J Appl Physiol, December 1, 2005; 99(6): 2189 - 2195. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
O. A. Sanchez, L. M. Snow, D. A. Lowe, R. C. Serfass, and L. V. Thompson Effects of endurance exercise-training on single-fiber contractile properties of insulin-treated streptozotocin-induced diabetic rats J Appl Physiol, August 1, 2005; 99(2): 472 - 478. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
| Visit Other APS Journals Online |
