Chemoreceptor sensitivity in adaptation to high altitude

Studies were carried out in a group of 20 young male subjects to investigate the changes in chemoreceptor sensitivity during acclimatization to altitude. Their hypoxic sensitivity and carbon dioxide sensitivity were studied at Delhi, during acclimatization at 3500 m, and on return to sea level. Similar studies were also done in a group of 10 acclimatized lowlanders who stayed at 3500-4000 m for 12-14 months, and also on 10 high-altitude natives. The results showed no significant alteration in the hypoxic sensitivity of the lowlanders; but CO2 sensitivity was markedly elevated at altitude, both in sojourners and acclimatized lowlanders. The high-altitude natives showed less sensitivity to hypoxia, whereas the CO2 sensitivity was normal.