Improved high altitude hypoxic tolerance and amelioration of anorexia and hypophagia in rats on oral glutamate supplementation

Background: The objective of this study is to evaluate the efficacy of oral glutamic acid supplementation in promoting hypoxic tolerance. Methods: The experiments were conducted in albino rats by exposing them to three levels of hypoxia in a simulated environment for Varying periods of time. The par ameters studied include: gasping time at 35,000 ft (10,668 m), food and wat er intake, and heart to body weight (b.w.) ratio at 25,000 ft (7620 m), tol erance to composite stress at 15,000 ft (4572 m) and biodistribution of glu tamate (glu). Results: Supplementation of Glu (27 mg kg(-1) b.w.) as glutam ic acid dissolved in normal saline resulted in 4.8 times enhanced hypoxic t olerance (time taken for appearance of first gasp), 23% body weight gain an d 24% increase in food consumption over control during hypoxia. When animal s were subjected to composite stress of cold, hypoxia and restraint (CHR), the Glu fed animals showed higher resistance to fall in rectal temperature than the control group. Hypoxia significantly enhanced heart to body weight ratio compared with control, and Glu supplementation reduced and brought i t down to that of control. Conclusion: The study reveals that Glu in optima l doses may be a conditionally essential amino acid resulting in enhanced t olerance to hypoxia and cold.