Survival of Infant and Adult Rats at High Altitudes.

SummaryInfant rats can tolerate a low oxygen concentration (3.87%) at high altitudes (40,000 feet) longer than adults of the same species. This tolerance decreases with age and is probably associated with the lower cerebral metabolism of infant brain.2 The diminution of metabolic rate of adult rats by thyroidectomy increases the resistance of these animals to high altitudes.3 The importance of the factor of aeroembolism in this differential survival has not been determined.