High-Intensity Training Represses FXYD5 and Glycosylates Na,K-ATPase in Type II Muscle Fibres, Which Are Linked with Improved Muscle K + Handling and Performance

• Published in: International journal of molecular sciences 2023-03, Vol.24 (6), p.5587
• Main Authors: Hostrup, Morten, Lemminger, Anders Krogh, Thomsen, Laura Bachmann, Schaufuss, Amanda, Alsøe, Tobias Langballe, Bergen, Gustav Krogh, Bell, Annika Birring, Bangsbo, Jens, Thomassen, Martin
• Format: Article
• Language: English
• Subjects: Abundance; Adaptation; Adenosine triphosphatase; Adult; ATPase; Exercise - physiology; Female; Fitness training programs; FXYD; Glycosylation; Heterogeneity; High-Intensity Interval Training; Hormones; Humans; Ion Channels; Male; Metabolism; Microfilament Proteins; Muscle contraction; Muscle Fibers, Skeletal - metabolism; Muscle function; Muscle, Skeletal - metabolism; Muscles; Muscular function; Musculoskeletal system; Na+/K+-exchanging ATPase; Na-K; NKA; Oxygen consumption; Pharmaceutical industry; phospholemman; Physical training; Plasma; pump; Sex differences; Skeletal muscle; Sodium-Potassium-Exchanging ATPase - metabolism; Spinal cord injuries; Young Adult
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms24065587

Na /K ATPase (NKA) comprises several subunits to provide isozyme heterogeneity in a tissue-specific manner. An abundance of NKA α, β, and FXYD1 subunits is well-described in human skeletal muscle, but not much is known about FXYD5 (dysadherin), a regulator of NKA and β1 subunit glycosylation, especially with regard to fibre-type specificity and influence of sex and exercise training. Here, we investigated muscle fibre-type specific adaptations in FXYD5 and glycosylated NKAβ1 to high-intensity interval training (HIIT), as well as sex differences in FXYD5 abundance. In nine young males (23.8 ± 2.5 years of age) (mean ± SD), 3 weekly sessions of HIIT for 6 weeks enhanced muscle endurance (220 ± 102 vs. 119 ± 99 s, < 0.01) and lowered leg K release during intense knee-extensor exercise (0.5 ± 0.8 vs. 1.0 ± 0.8 mmol·min , < 0.01) while also increasing cumulated leg K reuptake 0-3 min into recovery (2.1 ± 1.5 vs. 0.3 ± 0.9 mmol, < 0.01). In type IIa muscle fibres, HIIT lowered FXYD5 abundance ( < 0.01) and increased the relative distribution of glycosylated NKAβ1 ( < 0.05). FXYD5 abundance in type IIa muscle fibres correlated inversely with the maximal oxygen consumption ( = -0.53, < 0.05). NKAα2 and β1 subunit abundances did not change with HIIT. In muscle fibres from 30 trained males and females, we observed no sex ( = 0.87) or fibre type differences ( = 0.44) in FXYD5 abundance. Thus, HIIT downregulates FXYD5 and increases the distribution of glycosylated NKAβ1 in type IIa muscle fibres, which is likely independent of a change in the number of NKA complexes. These adaptations may contribute to counter exercise-related K shifts and enhance muscle performance during intense exercise.