Excretion of Lactic Acid by Rats Exposed to Simulated High Altitude.
DEFENCE AND CIVIL INST OF ENVIRONMENTAL MEDICINE DOWNSVIEW (ONTARIO)
Pagination or Media Count:
Plasma and urinary levels of lactic acid were measured in rats exposed to simulated altitudes of 18,000, 24,000 and 26,000 ft for six hr periods. Acute exposure six hr to 18,000 ft. did not alter the basal level of lactic acid excretion but 5-fold and 50-fold increases were found in animals after six hr at 24,000 and 26,000 ft, respectively. A large interindividual variability in lactic acid excretion was observed at 24,000 and 26,000 ft with values ranging from 4 to 1,000mg25mg urinary creatinine. Injection of adrenalin increased urinary lactate levels at altitude whereas prior fasting eliminated altitude-induced increases in lactic acid. It is suggested that at altitude, lactic acid formation from liver glycogen is, in part, mediated by increased adrenalin secretion and that when blood lactate exceeds a critical level 14 - 19mg percent, lactic acid increases in the urine. Modified author abstract
- Stress Physiology