Calcium phosphorus metabolism in man during acclimatization to carbon dioxide

Abstract

The calcium phosphorus metabolism was studied in 20 subjects who were exposed for 42 days to 1.5% CO₂. Plasma calcium mirrored the changes of the pH, showing a decrease during the first 23 days of exposure, a return to initial levels during the latter part of exposure, a marked rise above control values during the 8–9 day recovery period following exposure, and a return to normal values after 4 weeks of recovery. Changes in plasma calcium were found to correspond to changes in pulmonary CO₂ excretion indicating a significant role of bone CO₂ stores in acclimatization and deacclimatization of carbon dioxide. Plasma inorganic phosphorus was elevated throughout the exposure period and recovery period. At the end of the exposure period to CO₂ red cell calcium had increased and red cell phosphorus had decreased. After 9 days, as well as after 4 weeks, of recovery on air the calcium content of the red cells continued to increase and the inorganic phosphorus values remained lowered. chronic respiratory acidosis; chronic hypercapnia Submitted on November 2, 1961