In:
The Journal of Physiology, Wiley, Vol. 600, No. 12 ( 2022-06), p. 2897-2917
Abstract:
Sprint interval training (SIT) causes fragmentation of the skeletal muscle sarcoplasmic reticulum Ca 2+ release channel, ryanodine receptor 1 (RyR1), 24 h post‐exercise, potentially signalling mitochondrial biogenesis by increasing cytosolic [Ca 2+ ]. Yet, the time course and skeletal muscle fibre type‐specific patterns of RyR1 fragmentation following a session of SIT remain unknown. Ten participants ( n = 4 females; n = 6 males) performed a session of SIT (6 × 30 s ‘all‐out’ with 4.5 min rest after each sprint) with vastus lateralis muscle biopsy samples collected before and 3, 6 and 24 h after exercise. In whole muscle, full‐length RyR1 protein content was significantly reduced 6 h (mean (SD); −38 (38)%; P 〈 0.05) and 24 h post‐SIT (−30 (48)%; P 〈 0.05) compared to pre‐exercise. Examining each participant's largest response in pooled samples, full‐length RyR1 protein content was reduced in type II (−26 (30)%; P 〈 0.05) but not type I fibres (−11 (40)%; P 〉 0.05). Three hours post‐SIT, there was also a decrease in sarco(endo)plasmic reticulum Ca 2+ ATPase 1 in type II fibres (−23 (17)%; P 〈 0.05) and sarco(endo)plasmic reticulum Ca 2+ ATPase 2a in type I fibres (−19 (21)%; P 〈 0.05), despite no time effect for either protein in whole muscle samples ( P 〉 0.05). PGC1A mRNA content was elevated 3 and 6 h post‐SIT (5.3‐ and 3.7‐fold change from pre, respectively; P 〈 0.05 for both), but peak PGC1A mRNA expression was not significantly correlated with peak RyR1 fragmentation ( r 2 = 0.10; P 〉 0.05). In summary, altered Ca 2+ ‐handling protein expression, which occurs primarily in type II muscle fibres, may influence signals for mitochondrial biogenesis as early as 3–6 h post‐SIT in humans. Key points Sprint interval training (SIT) has been shown to cause fragmentation of the sarcoplasmic reticulum calcium‐release channel, ryanodine receptor 1 (RyR1), 24 h post‐exercise, which may act as a signal for mitochondrial biogenesis. In this study, the time course was examined of RyR1 fragmentation in human whole muscle and pooled type I and type II skeletal muscle fibres following a single session of SIT. Full‐length RyR1 protein content was significantly lower than pre‐exercise by 6 h post‐SIT in whole muscle, and fragmentation was detectable in type II but not type I fibres, though to a lesser extent than in whole muscle. The peak in PGC1A mRNA expression occurred earlier than RyR1 fragmentation. The increased temporal resolution and fibre type‐specific responses for RyR1 fragmentation provide insights into its importance to mitochondrial biogenesis in humans.
Type of Medium:
Online Resource
ISSN:
0022-3751
,
1469-7793
Language:
English
Publisher:
Wiley
Publication Date:
2022
detail.hit.zdb_id:
1475290-6
SSG:
12
Permalink
