Document Detail

Unchanged [3H]ouabain binding site content but reduced Na+-K+ pump α2-protein abundance in skeletal muscle in older adults.
MedLine Citation:
PMID:  22936730     Owner:  NLM     Status:  MEDLINE    
Aging is associated with reduced muscle mass, weakness, and increased fatigability. In skeletal muscle, the Na(+)-K(+) pump (NKA) is important in regulating Na(+)-K(+) gradients, membrane excitability, and thus contractility, but the effects of aging on muscle NKA are unclear. We investigated whether aging is linked with reduced muscle NKA by contrasting muscle NKA isoform gene expression and protein abundance, and NKA total content in 17 Elderly (66.8 ± 6.4 yr, mean ± SD) and 16 Young adults (23.9 ± 2.2 yr). Participants underwent peak oxygen consumption assessment and a vastus lateralis muscle biopsy, which was analyzed for NKA α(1)-, α(2)-, α(3)-, β(1)-, β(2)-, and β(3)-isoform gene expression (real-time RT-PCR), protein abundance (immunoblotting), and NKA total content ([(3)H]ouabain binding sites). The Elderly had lower peak oxygen consumption (-36.7%, P = 0.000), strength (-36.3%, P = 0.001), NKA α(2)- (-24.4%, 11.9 ± 4.4 vs. 9.0 ± 2.7 arbitrary units, P = 0.049), and NKA β(3)-protein abundance (-23.0%, P = 0.041) than Young. The β(3)-mRNA was higher in Elderly compared with Young (P = 0.011). No differences were observed between groups for other NKA isoform mRNA or protein abundance, or for [(3)H]ouabain binding site content. Thus skeletal muscle in elderly individuals was characterized by decreased NKA α(2)- and β(3)-protein abundance, but unchanged α(1) abundance and [(3)H]ouabain binding. The latter was likely caused by reduced α(2) abundance with aging, preventing an otherwise higher [(3)H]ouabain binding that might occur with a greater membrane density in smaller muscle fibers. Further study is required to verify reduced muscle NKA α(2) with aging and possible contributions to impaired exercise capability and daily living activities.
Michael J McKenna; Ben D Perry; Fabio R Serpiello; Marissa K Caldow; Pazit Levinger; David Cameron-Smith; Itamar Levinger
Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't     Date:  2012-08-30
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  113     ISSN:  1522-1601     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2012 Nov 
Date Detail:
Created Date:  2012-11-16     Completed Date:  2013-04-29     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:  1505-11     Citation Subset:  IM    
Institute of Sport, Exercise and Active Living, Muscle, Ions and Exercise Group, Victoria University, Melbourne, VIC 8001, Australia.
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MeSH Terms
Adenosine Triphosphatases / metabolism
Age Factors
Aging / metabolism*
Binding Sites
Blotting, Western
Cation Transport Proteins / metabolism
Cell Adhesion Molecules, Neuronal / metabolism
Exercise Test
Isometric Contraction
Middle Aged
Muscle Strength
Ouabain / metabolism*
Oxygen Consumption
Quadriceps Muscle / enzymology*
RNA, Messenger / metabolism
Real-Time Polymerase Chain Reaction
Sodium-Potassium-Exchanging ATPase / genetics,  metabolism*
Young Adult
Reg. No./Substance:
0/ATP1B2 protein, human; 0/Cation Transport Proteins; 0/Cell Adhesion Molecules, Neuronal; 0/RNA, Messenger; 10028-17-8/Tritium; 630-60-4/Ouabain; EC 3.6.1.-/ATP1A1 protein, human; EC 3.6.1.-/ATP1A2 protein, human; EC 3.6.1.-/Adenosine Triphosphatases; EC protein, human; EC protein, human; EC protein, human; EC ATPase

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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