Document Detail

Exercise increases the plasma membrane content of the Na+ -K+ pump and its mRNA in rat skeletal muscles.
MedLine Citation:
PMID:  8929618     Owner:  NLM     Status:  MEDLINE    
Muscle fibers adapt to ionic challenges of exercise by increasing the plasma membrane Na+-K+ pump activity. Chronic exercise training has been shown to increase the total amount of Na+-K+ pumps present in skeletal muscle. However, the mechanism of adaptation of the Na+-K+ pump to an acute bout of exercise has not been determined, and it is not known whether it involves alterations in the content of plasma membrane pump subunits. Here we examine the effect of 1 h of treadmill running (20 m/min, 10% grade) on the subcellular distribution and expression of Na+-K+ pump subunits in rat skeletal muscles. Red type I and IIa (red-I/IIa) and white type IIa and IIb (white-IIa/IIb) hindlimb muscles from resting and exercised female Sprague-Dawley rats were removed for subcellular fractionation. By homogenization and gradient centrifugation, crude membranes and purified plasma membranes were isolated and subjected to gel electrophoresis and immunoblotting by using pump subunit-specific antibodies. Furthermore, mRNA was isolated from specific red type I (red-I) and white type IIb (white-IIb) muscles and subjected to Northern blotting by using subunit-specific probes. In both red-I/IIa and white-IIa/IIb muscles, exercise significantly raised the plasma membrane content of the alpha1-subunit of the pump by 64 +/- 24 and 55 +/- 22%, respectively (P < 0.05), and elevated the alpha2-polypeptide by 43 +/- 22 and 94 +/- 39%, respectively (P < 0.05). No significant effect of exercise could be detected on the amount of these subunits in an internal membrane fraction or in total membranes. In addition, exercise significantly increased the alpha1-subunit mRNA in red-I muscle (by 50 +/- 7%; P < 0.05) and the beta2-subunit mRNA in white-IIb muscles (by 64 +/- 19%; P < 0.01), but the alpha2- and beta1-mRNA levels were unaffected in this time period. We conclude that increased presence of alpha1- and alpha2-polypeptides at the plasma membrane and subsequent elevation of the alpha1- and beta2-subunit mRNAs may be mechanisms by which acute exercise regulates the Na+-K+ pump of skeletal muscle.
T Tsakiridis; P P Wong; Z Liu; C D Rodgers; M Vranic; A Klip
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  80     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  1996 Feb 
Date Detail:
Created Date:  1997-02-06     Completed Date:  1997-02-06     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  699-705     Citation Subset:  IM; S    
Division of Cell Biology, The Hospital for Sick Children, Toronto, Canada.
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MeSH Terms
Antibodies, Monoclonal / diagnostic use
Blotting, Northern
Cell Membrane / enzymology
Electric Stimulation
Muscle, Skeletal / enzymology*,  ultrastructure
Physical Exertion / physiology*
RNA, Messenger / biosynthesis*,  isolation & purification
Rats, Sprague-Dawley
Sodium-Potassium-Exchanging ATPase / biosynthesis*,  physiology*
Subcellular Fractions / enzymology,  physiology
Reg. No./Substance:
0/Antibodies, Monoclonal; 0/RNA, Messenger; EC ATPase

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