Combined effects of hypoxia and endurance training on lipid metabolism in rat skeletal muscle

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Abstract:

Abstract Aim: 

To determine whether endurance training can counterbalance the negative effects of hypoxia on mitochondrial phosphorylation and expression of the long chain mitochondrial fatty acid transporter muscle carnitine palmitoyl transferase 1 (mCPT-1). Methods: 

Male Wistar rats were exposed either to hypobaric hypoxia (at a simulated altitude of ≈4000 m, PIO2 ≈ 90 mmHg) or to normoxia (sea level) for 5 weeks. In each environment, rats were randomly assigned to two groups. The trained group went through a 5-week endurance training programme. The control group remained sedentary for the same time period. Muscle fatty acid oxidation capacity was evaluated after the 5-week period on isolated mitochondria prepared from quadriceps muscles with the use of palmitoylcarnitine or pamitoylCoA + carnitine. Results: 

Chronic hypoxia decreased basal (V0, −31% with pamitoylCoA + carnitine and −21% with palmitoylcarnitine, P <0.05) and maximal (Vmax, −31% with pamitoylCoA + carnitine, P <0.05) respiration rates, hydroxyacylCoA dehydrogenase activity (−48%, P <0.05), mCPT-1 activity index (−34%, P <0.05) and mCPT-1 protein content (−34%, P <0.05). Five weeks of endurance training in hypoxia brought V0, mCPT-1 activity index and mCPT-1 protein content values back to sedentary normoxic levels. Moreover, in the group trained in hypoxia, Vmax reached a higher level than in the group that maintained a sedentary lifestyle in normoxia (24.2 nmol O2· min−1 · mg−1 for hypoxic training vs. 19.9 nmol O2 · min−1 · mg−1 for normoxic sedentarity, P <0.05). Conclusion: 

Endurance training can attenuate chronic hypoxia-induced impairments in mitochondrial fatty acid oxidation. This training effect seems mostly mediated by mCPT-1 activity rather than by mCPT-1 content.

Keywords: chronic hypoxia; endurance training; fatty acid oxidation; mCPT-1; mitochondria

Document Type: Research Article

DOI: http://dx.doi.org/10.1111/j.1748-1716.2007.01794.x

Affiliations: 1:  EA 2426, Physiologie des Adaptations Cardio-vasculaires à l’Exercice, Université d’Avignon, Avignon, France 2:  EA 3759, Approche Bio-psycho-sociale du Dopage, UFR STAPS, Université Montpellier 1, Montpellier, France 3:  INSERM ERI 25, Muscle et Pathologies, Montpellier, France

Publication date: June 1, 2008

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