Skeletal muscle ATP turnover by 31P magnetic resonance spectroscopy during moderate and heavy bilateral knee extension
| Autor: | Daniel T. Cannon, Scott R. Murgatroyd, Sophie A. Hampson, T. Scott Bowen, Harry B. Rossiter, Simon Marwood, W.E. Bimson, Graham J. Kemp |
|---|---|
| Rok vydání: | 2014 |
| Předmět: |
Adult
Male medicine.medical_specialty Magnetic Resonance Spectroscopy Phosphocreatine Physiology Journal Club Knee extension Oxidative Phosphorylation chemistry.chemical_compound Young Adult Adenosine Triphosphate Oxygen Consumption Internal medicine medicine Humans Glycolysis Atp turnover Anaerobiosis Exercise physiology Muscle Skeletal Exercise Chemistry Pulmonary Gas Exchange Skeletal muscle Nuclear magnetic resonance spectroscopy Oxygen uptake Surgery Mitochondria Muscle Oxygen Endocrinology medicine.anatomical_structure Muscle Female human activities Muscle Contraction |
| Zdroj: | The Journal of physiology. 592(23) |
| ISSN: | 1469-7793 |
| Popis: | During constant-power high-intensity exercise, the expected increase in oxygen uptake (V̇O2) is supplemented by a V̇O2 slow component (V̇O2 sc ), reflecting reduced work efficiency, predominantly within the locomotor muscles. The intracellular source of inefficiency is postulated to be an increase in the ATP cost of power production (an increase in P/W). To test this hypothesis, we measured intramuscular ATP turnover with (31)P magnetic resonance spectroscopy (MRS) and whole-body V̇O2 during moderate (MOD) and heavy (HVY) bilateral knee-extension exercise in healthy participants (n = 14). Unlocalized (31)P spectra were collected from the quadriceps throughout using a dual-tuned ((1)H and (31)P) surface coil with a simple pulse-and-acquire sequence. Total ATP turnover rate (ATPtot) was estimated at exercise cessation from direct measurements of the dynamics of phosphocreatine (PCr) and proton handling. Between 3 and 8 min during MOD, there was no discernable V̇O2 sc (mean ± SD, 0.06 ± 0.12 l min(-1)) or change in [PCr] (30 ± 8 vs. 32 ± 7 mm) or ATPtot (24 ± 14 vs. 17 ± 14 mm min(-1); each P = n.s.). During HVY, the V̇O2 sc was 0.37 ± 0.16 l min(-1) (22 ± 8%), [PCr] decreased (19 ± 7 vs. 18 ± 7 mm, or 12 ± 15%; P 0.05) and ATPtot increased (38 ± 16 vs. 44 ± 14 mm min(-1), or 26 ± 30%; P 0.05) between 3 and 8 min. However, the increase in ATPtot (ΔATPtot) was not correlated with the V̇O2 sc during HVY (r(2) = 0.06; P = n.s.). This lack of relationship between ΔATPtot and V̇O2 sc , together with a steepening of the [PCr]-V̇O2 relationship in HVY, suggests that reduced work efficiency during heavy exercise arises from both contractile (P/W) and mitochondrial sources (the O2 cost of ATP resynthesis; P/O). |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Plný text