AJP - Endo Journal of Neurophysiology
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH
QUICK SEARCH:   [advanced]


     

Am J Physiol Endocrinol Metab (October 25, 2005). doi:10.1152/ajpendo.00395.2005
This Article
Right arrow Full Text (PDF)
Right arrow All Versions of this Article:
290/3/E583    most recent
00395.2005v1
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 Toyoda, T.
Right arrow Articles by Hayashi, T.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Toyoda, T.
Right arrow Articles by Hayashi, T.
Submitted on August 23, 2005
Accepted on October 20, 2005

Low-intensity contraction activates the {alpha}1 isoform of 5'AMP-activated protein kinase in rat skeletal muscle

Taro Toyoda1, Satsuki Tanaka2, Ken Ebihara2, Hiroaki Masuzaki2, Kiminori Hosoda2, Kenji Sato3, Tohru Fushiki1, Kazuwa Nakao2, and Tatsuya Hayashi4*

1 Laboratory of Nutrition Chemistry, Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
2 Department of Medicine and Clinical Science, Graduate School of Medicine, Kyoto University, Kyoto, Japan
3 Laboratory of Food Science, Department of Food Sciences and Nutritional Health, Kyoto Prefectural University, Kyoto, Japan
4 Laboratory of Sports and Exercise Medicine, Graduate School of Human and Environmental Studies, Kyoto University, Kyoto, Japan

* To whom correspondence should be addressed. E-mail: tatsuya{at}kuhp.kyoto-u.ac.jp.

Skeletal muscle expresses two catalytic subunits, {alpha}1 and {alpha}2, of the 5'AMP-activated protein kinase (AMPK), which has been implicated in the contraction-stimulated glucose transport and fatty acid oxidation. Muscle contraction activates the {alpha}2-containing AMPK complex (AMPK{alpha}2), but this activation may occur with or without activation of the {alpha}1-containing AMPK complex (AMPK{alpha}1), suggesting that AMPK{alpha}2 is the major isoform responsible for contraction-induced metabolic events in skeletal muscle. We report for the first time that AMPK{alpha}1, but not AMPK{alpha}2, can be activated in contracting skeletal muscle. Rat epitrochlearis muscles were isolated and incubated in Krebs-Ringer bicarbonate buffer containing pyruvate. In muscles stimulated to contract at a frequency of 1 Hz and 2 Hz during the last 2 min of incubation, AMPK{alpha}1 activity increased by 2-fold and AMPK{alpha}2 activity remained unchanged. Muscle stimulation did not change the muscle AMP concentration or the AMP:ATP ratio. AMPK activation was associated with increased phosphorylation of Thr172 of the {alpha} subunit, the primary activation site. Muscle stimulation increased the phosphorylation of acetyl-CoA carboxylase (ACC), a downstream target of AMPK, and the rate of 3-O-methyl-D-glucose transport. In contrast, increasing the frequency (> 5 Hz) or duration (> 5 min) of contraction activated AMPK{alpha}1 and AMPK{alpha}2, increased AMP concentration and the AMP:ATP ratio. These results suggest that 1) AMPK{alpha}1 is the predominant isoform activated by an AMP-independent phosphorylation in low-intensity contracting muscle, 2) AMPK{alpha}2 is activated by an AMP-dependent mechanism in high-intensity contracting muscle, and 3) activation of each isoform enhances glucose transport and ACC phosphorylation in skeletal muscle.




This article has been cited by other articles:


Home page
 Am. J. Physiol. Endocrinol. Metab.Home page
V. Ljubicic and D. A. Hood
Kinase-specific responsiveness to incremental contractile activity in skeletal muscle with low and high mitochondrial content
Am J Physiol Endocrinol Metab, July 1, 2008; 295(1): E195 - E204.
[Abstract] [Full Text] [PDF]

Home page
 J. Appl. Physiol.Home page
M. J. Drummond, H. C. Dreyer, B. Pennings, C. S. Fry, S. Dhanani, E. L. Dillon, M. Sheffield-Moore, E. Volpi, and B. B. Rasmussen
Skeletal muscle protein anabolic response to resistance exercise and essential amino acids is delayed with aging
J Appl Physiol, May 1, 2008; 104(5): 1452 - 1461.
[Abstract] [Full Text] [PDF]

Home page
 J. Physiol.Home page
S. L. McGee, K. J. Mustard, D. G. Hardie, and K. Baar
Normal hypertrophy accompanied by phosphoryation and activation of AMP-activated protein kinase {alpha}1 following overload in LKB1 knockout mice
J. Physiol., March 15, 2008; 586(6): 1731 - 1741.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Physiol. Endocrinol. Metab.Home page
T. E. Jensen, A. J. Rose, Y. Hellsten, J. F. P. Wojtaszewski, and E. A. Richter
Caffeine-induced Ca2+ release increases AMPK-dependent glucose uptake in rodent soleus muscle
Am J Physiol Endocrinol Metab, July 1, 2007; 293(1): E286 - E292.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Physiol. Endocrinol. Metab.Home page
T. E. Jensen, A. J. Rose, S. B. Jorgensen, N. Brandt, P. Schjerling, J. F. P. Wojtaszewski, and E. A. Richter
Possible CaMKK-dependent regulation of AMPK phosphorylation and glucose uptake at the onset of mild tetanic skeletal muscle contraction
Am J Physiol Endocrinol Metab, May 1, 2007; 292(5): E1308 - E1317.
[Abstract] [Full Text] [PDF]


HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH
Visit Other APS Journals Online
Copyright © 2005 by the American Physiological Society.