Time Course of Respiratory Adaptation to High Altitude.
Final rept. 1 Jul 67-30 Sep 68,
COLORADO UNIV DENVER MEDICAL CENTER
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The investigation was undertaken to examine cardiopulmonary adaptations of man to moderately high altitude. Emphasis was placed upon defining the time course of adaptation by examing groups of individuals exposed to chronic hypoxia for periods ranging from 4 days to 31 years. During the first weeks of exposure to high altitude, adaptations in respiratory control are not adequately explained by the popular concepts of hypoxic stimulation of peripheral chemoreceptors, with the resultant hyperventilation causing respiratory alkalosis and a reduction in hydrogen ion concentration of the cerebrospinal fluid CSF which is subsequently restored. Rather, exercise plus hypoxia enhance to sensitivity of the peripheral chemoreceptors, while changes in the pH of CSF are minimal and of little significance. With years of exposure to chronic hypoxia, there is a progressive diminution in the ventilatory response to hypoxic stimulation of the peripheral chemoreceptors. Consequently, the minimal ventilatory response to acute hypoxia seen in men native to high altitude is a trait acquired from many years of exposure to chronic hypoxia, rather than being dependent upon exposure to hypoxia continuously from the time of birth. Author
- Stress Physiology