title: Intense exercise up-regulates Na+,K+-ATPase isoform mRNA, but not protein expression in human skeletal muscle.
abstract: 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 approximately 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 alpha(1), alpha(2), alpha(3), beta(1), beta(2) and beta(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 alpha(3) and beta(2) mRNA by 2.4- and 1.7-fold, respectively (P < 0.05), whilst alpha(1) and alpha(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 beta(1) and beta(3) mRNA, reflecting variable time-dependent responses. When the average postexercise value was contrasted to rest, mRNA increased for alpha(1), alpha(2), alpha(3), beta(1), beta(2) and beta(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 alpha(1)-alpha(3) and beta(1)-beta(3) isoforms. Thus, human skeletal muscle expresses each of the Na(+),K(+)-ATPase alpha(1), alpha(2), alpha(3), beta(1), beta(2) and beta(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.
authors.affiliation: School of Human Movement, Recreation and Performance (FO22), Victoria University of Technology, PO Box 14428, MCMC, Melbourne, Victoria, Australia.
authors.forename: K T
authors.initials: KT
authors.lastname: Murphy
authors.forename: R J
authors.initials: RJ
authors.lastname: Snow
authors.forename: A C
authors.initials: AC
authors.lastname: Petersen
authors.forename: R M
authors.initials: RM
authors.lastname: Murphy
authors.forename: J
authors.initials: J
authors.lastname: Mollica
authors.forename: J S
authors.initials: JS
authors.lastname: Lee
authors.forename: A P
authors.initials: AP
authors.lastname: Garnham
authors.forename: R J
authors.initials: RJ
authors.lastname: Aughey
authors.forename: J A
authors.initials: JA
authors.lastname: Leppik
authors.forename: I
authors.initials: I
authors.lastname: Medved
authors.forename: D
authors.initials: D
authors.lastname: Cameron-Smith
authors.forename: M J
authors.initials: MJ
authors.lastname: McKenna
mesh_terms: D000328:Adult; D002478:Cells, Cultured; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D007527:Isoenzymes / Q000235:genetics*; D008297:Male; D018485:Muscle Fibers, Skeletal / Q000166:cytology / Q000201:enzymology; D018482:Muscle, Skeletal / Q000166:cytology / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000235:genetics* / Q000378:metabolism; D015854:Up-Regulation / Q000502:physiology
chemical_list: D007527:Isoenzymes; D012333:RNA, Messenger; D000254:Sodium-Potassium-Exchanging ATPase