AJP - Regu Information on EB 2010
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH
QUICK SEARCH:   [advanced]


     

Am J Physiol Regul Integr Comp Physiol (December 12, 2007). doi:10.1152/ajpregu.00541.2007
This Article
Right arrow Full Text (PDF)
Right arrow Supplemental Information
Right arrow All Versions of this Article:
294/3/R948    most recent
00541.2007v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Karatzaferi, C.
Right arrow Articles by Cooke, R.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Karatzaferi, C.
Right arrow Articles by Cooke, R.
Submitted on July 27, 2007
Accepted on December 11, 2007

THE INHIBITION OF SHORTENING VELOCITY OF SKINNED SKELETAL MUSCLE FIBERS IN CONDITIONS THAT MIMIC FATIGUE

Christina Karatzaferi1, Kathleen Franks-Skiba2, and Roger Cooke2*

1 Biochemistry & Biophysics and Cardiovascular Research Institute, University of Thessaly, Trikala, Greece
2 Biochemistry & Biophysics and Cardiovascular Research Institute, UCSF, San Francisco, California, United States

* To whom correspondence should be addressed. E-mail: cooke{at}cgl.ucsf.edu.

The mechanisms responsible for the inhibition of shortening velocity that occurs during muscle fatigue have not been completely elucidated. Phosphorylation of the myosin regulatory light chain (RLC) occurs during heavy use, however previous reports on its role in affecting velocity have been equivocal. To further understand the process of fatigue we varied the levels of myosin RLC phosphorylation (from 10% to >50%), the concentrations of protons (from pH 7 to 6.2) and phosphate (from 5 mM to 30 mM), all of which change during fatigue. We measured the mechanics of permeable rabbit psoas fibers at a temperature closer to physiological, 30°C, using a temperature jump protocol to briefly activate the fibers at the higher temperature in order to preserve sarcomere homogeneity. While lowered pH alone had an effect on velocity, it was the three factors together, i.e. high phosphorylation, low pH and high phosphate, which acted synergistically to inhibit fiber velocity by approx. 40%. Our data demonstrate that, in conditions that simulate physiological muscle fatigue, myosin phosphorylation does contribute to the inhibition of contraction velocity of fully activated fast muscle fibers.




This article has been cited by other articles:


Home page
 Am. J. Physiol. Regul. Integr. Comp. Physiol.Home page
M. Munkvik, P. K. Lunde, and O. M. Sejersted
Causes of fatigue in slow-twitch rat skeletal muscle during dynamic activity
Am J Physiol Regulatory Integrative Comp Physiol, September 1, 2009; 297(3): R900 - R910.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Physiol. Regul. Integr. Comp. Physiol.Home page
M. J. Greenberg, T. R. Mealy, J. D. Watt, M. Jones, D. Szczesna-Cordary, and J. R. Moore
The molecular effects of skeletal muscle myosin regulatory light chain phosphorylation
Am J Physiol Regulatory Integrative Comp Physiol, August 1, 2009; 297(2): R265 - R274.
[Abstract] [Full Text] [PDF]

Home page
 J. Appl. Physiol.Home page
H. Roots, G. Ball, J. Talbot-Ponsonby, M. King, K. McBeath, and K. W. Ranatunga
Muscle fatigue examined at different temperatures in experiments on intact mammalian (rat) muscle fibers
J Appl Physiol, February 1, 2009; 106(2): 378 - 384.
[Abstract] [Full Text] [PDF]


HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH
Visit Other APS Journals Online
Copyright © 2007 by the American Physiological Society.