Effect of acute hypobaric hypoxia on skeletal muscle protein turnover

Abstract

Objective: Present study was designed to investigate the effects of altitude mediated acute hypobaric hypoxia on protein turnover in skeletal muscle. Background: Skeletal muscle wasting is considered to be an important factor leading to decrease in physical performance at high altitude. Changes in protein turnover and the mechanism underlying the loss of skeletal muscle mass under these conditions are not very well understood. Method: Male Sprague Dawley rats (n=12 each group) weighing about 180-200 g were exposed to hypobaric hypoxia (9144 m) for six hours. Skeletal muscle homogenates were prepared for carrying out various studies including proteolytic pathways. Result: Acute exposure to hypobaric hypoxia has deleterious effects on skeletal muscle mass which was reflected by one third attenuation in protein synthesis and more than 50 % increase in protein degradation. Hypobaric hypoxia resulted in upregulation of Ub-Proteasome pathway and calpain whereas lysosomal mediated proteolysis remained unchanged. Glutaminase activity, protein carbonyl status, oxidative stress markers were also found to be elevated in hypoxia exposed rats. Conclusion: These results are indicative of excessive protein degradation and decreased protein synthesis during acute hypobaric hypoxia. Moreover increased protein oxidation may also be an important contributor for the skeletal muscle loss.

Keywords

• hypobaric hypoxia
• protein turn over
• skeletal muscle atrophy
• oxidative stress