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Intense exercise up‐regulates Na + ,K + ‐ATPase isoform mRNA, but not protein expression in human skeletal muscle
Author(s) -
Murphy K. T.,
Snow R. J.,
Petersen A. C.,
Murphy R. M.,
Mollica J.,
Lee J. S.,
Garnham A. P.,
Aughey R. J.,
Leppik J. A.,
Medved I.,
CameronSmith D.,
McKenna M. J.
Publication year - 2004
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2003.054981
Subject(s) - skeletal muscle , gene isoform , alpha (finance) , medicine , endocrinology , messenger rna , beta (programming language) , gene expression , biology , microbiology and biotechnology , chemistry , biochemistry , gene , construct validity , nursing , computer science , patient satisfaction , programming language
Characterization of expression of, and consequently also the acute exercise effects on, Na + ,K + ‐ATPase isoforms in human skeletal muscle remains incomplete and was therefore investigated. Fifteen healthy subjects (eight males, seven females) performed fatiguing, knee extensor exercise at ∼40% of their maximal work output per contraction. A vastus lateralis muscle biopsy was taken at rest, fatigue and 3 and 24 h postexercise, and analysed for Na + ,K + ‐ATPase α 1 , α 2 , α 3 , β 1 , β 2 and β 3 mRNA and crude homogenate protein expression, using Real‐Time RT‐PCR and immunoblotting, respectively. Each individual expressed gene transcripts and protein bands for each Na + ,K + ‐ATPase isoform. Each isoform was also expressed in a primary human skeletal muscle cell culture. Intense exercise (352 ± 69 s; mean ± s.e.m. ) immediately increased α 3 and β 2 mRNA by 2.4‐ and 1.7‐fold, respectively ( P < 0.05), whilst α 1 and α 2 mRNA were increased by 2.5‐ and 3.5‐fold at 24 h and 3 h postexercise, respectively ( P < 0.05). No significant change occurred for β 1 and β 3 mRNA, reflecting variable time‐dependent responses. When the average postexercise value was contrasted to rest, mRNA increased for α 1 , α 2 , α 3 , β 1 , β 2 and β 3 isoforms, by 1.4‐, 2.2‐, 1.4‐, 1.1‐, 1.0‐ and 1.0‐fold, respectively ( P < 0.05). However, exercise did not alter the protein abundance of the α 1 –α 3 and β 1 –β 3 isoforms. Thus, human skeletal muscle expresses each of the Na + ,K + ‐ATPase α 1 , α 2 , α 3 , β 1 , β 2 and β 3 isoforms, evidenced at both transcription and protein levels. Whilst brief exercise increased Na + ,K + ‐ATPase isoform mRNA expression, there was no effect on isoform protein expression, suggesting that the exercise challenge was insufficient for muscle Na + ,K + ‐ATPase up‐regulation.