The Role of Adrenal Cortex in the Process of Acclimatization to High Altitudes

The first part refers to some indexes of adrenal function and cortisol metabolism in acute exposure of sea level natives to 4,300 meters of altitude. The results show the following a Cortisol secretion rate is temporarily increased correlating with increases in its plasma concentration and in the urinary excretion of its metabolites b Hypoxia does not result in a maximal stimulus for the adrenal cortex since it can be further stimulated by exogenous corticotrophin c The adrenocortical response to high altitude can be blocked by the administration of dexamethasone d The second compartment in which cortisol is distributed is diminished. This may be related with the contraction of the radiosulfate space, observed under the same experimental conditions and e The metabolic clearance rate of cortisol is not significantly altered. The second part refers to the study of corticotrophin half-life t 12. Our results indicate that a 24 aminoacids ACTH has a t 12 slightly longer than a 39 aminoacids ACTH. Using the same type of experiments the t 12 of the 39 aminoacids ACTH in 11 high altitude natives was also investigated. The results were similar to the ones obtained in the sea level controls.