ArticleThe Journal of general physiology2015
Na,K-ATPase α2 activity in mammalian skeletal muscle T-tubules is acutely stimulated by extracellular K+.
Article in The Journal of general physiology, 2015. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 39 papers.
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Who cites it
39 citing papers in PubMed, 65 citations in OpenAlex.
- Quantitative analysis of skeletal muscle contributions to ECF KAmerican journal of physiology. Cell physiology · 2026Review
- Extracellular KNature communications · 2026Article
- Potassium-sensitive loss of muscle force in the setting of reduced inward rectifier KProceedings of the National Academy of Sciences of the United States of America · 2025Article
- A century of exercise physiology: effects of muscle contraction and exercise on skeletal muscle NaEuropean journal of applied physiology · 2024Review
- Re-Thinking Hyperkalaemia Management in Chronic Kidney Disease-Beyond Food Tables and Nutrition Myths: An Evidence-Based Practice Review.Nutrients · 2023Review
- Short-Term Mild Hypoxia Modulates Na,K-ATPase to Maintain Membrane Electrogenesis in Rat Skeletal Muscle.International journal of molecular sciences · 2022Article
- Chronic Ouabain Prevents Radiation-Induced Reduction in the α2 Na,K-ATPase Function in the Rat Diaphragm Muscle.International journal of molecular sciences · 2022Article
- Potassium homeostasis: sensors, mediators, and targets.Pflugers Archiv : European journal of physiology · 2022Review
- Modulation of P2X4 pore closure by magnesium, potassium, and ATP.Biophysical journal · 2022Article
- Excitability properties of mouse and human skeletal muscle fibres compared by muscle velocity recovery cycles.Neuromuscular disorders : NMD · 2022Article
- Regulation of Cardiac Contractility by the Alpha 2 Subunit of the NaFrontiers in physiology · 2022Review
- The Na/K-ATPase α1/Src interaction regulates metabolic reserve and Western diet intolerance.Acta physiologica (Oxford, England) · 2021Article
- Chronic Ouabain Prevents Na,K-ATPase Dysfunction and Targets AMPK and IL-6 in Disused Rat Soleus Muscle.International journal of molecular sciences · 2021Article
- FXYD proteins and sodium pump regulatory mechanisms.The Journal of general physiology · 2021Review
- Regulation of muscle potassium: exercise performance, fatigue and health implications.European journal of applied physiology · 2021Review
- The role of AMPK in regulation of NaJournal of muscle research and cell motility · 2021Review
- Article
- FXYD protein isoforms differentially modulate human Na/K pump function.The Journal of general physiology · 2020Article
- Resistance training upregulates skeletal muscle NaEuropean journal of applied physiology · 2020Article
- Skeletal Muscle Na,K-ATPase as a Target for Circulating Ouabain.International journal of molecular sciences · 2020Article
Corrections and comments
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Authors and funding
4 authors at 2 institutions in 1 country.
Funding
Abstract
The Na,K-ATPase α2 isoform is the predominant Na,K-ATPase in adult skeletal muscle and the sole Na,K-ATPase in the transverse tubules (T-tubules). In quiescent muscles, the α2 isozyme operates substantially below its maximal transport capacity. Unlike the α1 isoform, the α2 isoform is not required for maintaining resting ion gradients or the resting membrane potential, canonical roles of the Na,K-ATPase in most other cells. However, α2 activity is stimulated immediately upon the start of contraction and, in working muscles, its contribution is crucial to maintaining excitation and resisting fatigue. Here, we show that α2 activity is determined in part by the K+ concentration in the T-tubules, through its K+ substrate affinity. Apparent K+ affinity was determined from measurements of the K1/2 for K+ activation of pump current in intact, voltage-clamped mouse flexor digitorum brevis muscle fibers. Pump current generated by the α2 Na,K-ATPase, Ip, was identified as the outward current activated by K+ and inhibited by micromolar ouabain. Ip was outward at all potentials studied (-90 to -30 mV) and increased with depolarization in the subthreshold range, -90 to -50 mV. The Q10 was 2.1 over the range of 22-37°C. The K1/2,K of Ip was 4.3±0.3 mM at -90 mV and was relatively voltage independent. This K+ affinity is lower than that reported for other cell types but closely matches the dynamic range of extracellular K+ concentrations in the T-tubules. During muscle contraction, T-tubule luminal K+ increases in proportion to the frequency and duration of action potential firing. This K1/2,K predicts a low fractional occupancy of K+ substrate sites at the resting extracellular K+ concentration, with occupancy increasing in proportion to the frequency of membrane excitation. The stimulation of preexisting pumps by greater K+ site occupancy thus provides a rapid mechanism for increasing α2 activity in working muscles.
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