| Unchanged [3H]ouabain binding site content but reduced Na+,K+-pump α2 protein abundance in skeletal muscle in older adults. | |
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MedLine Citation:
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PMID: 22936730 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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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 contractility, but the effects of aging on 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 yrs, Mean±SD) and 16 Young adults (23.9±2.2 yrs). Participants underwent peak oxygen consumption (VO(2peak)) assessment and a vastus lateralis muscle biopsy, which was analysed 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 VO(2peak) (-36.7%, P=0.000), strength (-36.3%, P=0.001), NKA α(2) protein abundance (-24.4%, 11.9±4.4 versus 9.0±2.7 arbitrary units, P=0.049) and NKA β(3) protein abundance (-23.0%, P=0.041) than Young, respectively. The β(3) mRNA was higher in Elderly compared to 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 characterised 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 fibres. Further study is required to verify reduced muscle NKA α(2) with aging and possible contributions to impaired exercise capability and daily living activities. |
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Authors:
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Michael John McKenna; Ben Douglas Perry; Fabio R Serpiello; Marissa Kate Caldow; Pazit Levinger; David Cameron-Smith; Itamar Levinger |
Publication Detail:
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Type: JOURNAL ARTICLE Date: 2012-8-30 |
Journal Detail:
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Title: Journal of applied physiology (Bethesda, Md. : 1985) Volume: - ISSN: 1522-1601 ISO Abbreviation: J. Appl. Physiol. Publication Date: 2012 Aug |
Date Detail:
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Created Date: 2012-8-31 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 8502536 Medline TA: J Appl Physiol Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
Affiliation:
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1Victoria University. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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