Cerebrospinal fluid in man native to high altitude

CSF pH was shown in a prior report to remain essentially constant during 8 days of acclimatization to 3,800 m. In order to further evaluate the possible role of CSF acid-base equilibria in the regulation of respiration, 20 Peruvian Andean natives were studied at altitudes of 3,720–4,820 m. In ten subjects at 3,720 m, means were: CSF pH 7.327, Pco 2 43, HCO 3 - 21.5, Na + 136, K + 2.6, Cl - 124, lactate 30 mg/100 ml. Arterial blood: pH 7.43, Pco 2 32.5, HCO 3 - 21.3, Na + 136, K + 4.2, Cl - 107, hematocrit 49, Sa O O2 89.6. In six subjects at 4,545 m and four at 4,820 m CSF values were not significantly different; mean arterial Pco 2 was 32.6 and 32.3, respectively. The only significant variations with altitude were the expected lowering of Pa O O2 to 47 and 43.5 mm Hg, and of Sa O O2 to 84.2 and 80.7, and increase of hematocrit to 67% and 75%, respectively. The natives differed from recently acclimatized sea-level residents in showing less ventilation (higher Pco 2 ) in response to the existing hypoxia, and less alkaline arterial blood. The difference appears to relate to peripheral chemoreceptor response to hypoxia rather than central medullary chemoreceptor. respiratory regulation at high altitude; chronic acclimatization to altitude; peripheral chemoreceptor response to hypoxia; CSF and medullary respiratory chemoreceptors Submitted on June 12, 1963