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Biochimie. 2018 May;148:36-45. doi: 10.1016/j.biochi.2018.02.014. Epub 2018 Feb 28.

Exercise training impacts exercise tolerance and bioenergetics in gastrocnemius muscle of non-obese type-2 diabetic Goto-Kakizaki rat in vivo.

Author information

1
Aix Marseille Univ, CNRS, CRMBM, Marseille, France.
2
Université Paris-Diderot, Sorbonne Paris Cité, Laboratoire B2PE, Unité BFA, CNRS EAC 4413, Paris, France.
3
Aix Marseille Univ, CNRS, CRMBM, Marseille, France. Electronic address: benoit.giannesini@univ-amu.fr.

Abstract

The functional and bioenergetics impact of regular physical activity upon type-2 diabetic skeletal muscle independently of confounding factors of overweight remains undocumented. Here, gastrocnemius muscle energy fluxes, mitochondrial capacity and mechanical performance were assessed noninvasively and longitudinally in non-obese diabetic Goto-Kakizaki rats using magnetic resonance (MR) imaging and dynamic 31-phosphorus MR spectroscopy (31P-MRS) throughout a 6-min fatiguing bout of exercise performed before, in the middle (4-week) and at the end of an 8-week training protocol consisting in 60-min daily run on a treadmill. The training protocol reduced plasmatic insulin level (-61%) whereas blood glucose and non-esterified fatty acids levels remained unaffected, thereby indicating an improvement of insulin sensitivity. It also increased muscle mitochondrial citrate synthase activity (+45%) but this increase did not enhance oxidative ATP synthesis capacity in working muscle in vivo while glycolytic ATP production was increased (+33%). On the other hand, the training protocol impaired maximal force-generating capacity (-9%), total amount of force produced (-12%) and increased ATP cost of contraction (+32%) during the fatiguing exercise. Importantly, these deleterious effects were transiently worsened in the middle of the 8-week period, in association with reduced oxidative capacity and increased basal [Pi]/[PCr] ratio (an in vivo biomarker of muscle damage). These data demonstrate that the beneficial effect of regular training on insulin sensitivity in non-obese diabetic rat occurs separately from any improvement in muscle mitochondrial function and might be linked to an increased capacity for metabolizing glucose through anaerobic process in exercising muscle.

KEYWORDS:

Diabetes; Mitochondrial capacity; Nuclear magnetic resonance; Regular physical activity; Skeletal muscle function

PMID:
29499298
DOI:
10.1016/j.biochi.2018.02.014
[Indexed for MEDLINE]

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