Relationship between hematocrit and CO2 contents in whole blood and true plasma.
The amount of CO2 liberated out of the red cell was measured by decreasing PCO2 in human blood with different fractional hematocrits of about 0.24, 0.45, and 0.75, respectively, in order to elucidate whether it depends on the hematocrit and the intracellular pH. From a venous PCO2 level the PCO2 of the sample blood was lowered to 12 Torr. PCO2, CO2 content, pH, Cl-, and Na+ were measured in whole blood and true plasma before and after the reduction of PCO2. Change in water concentration in plasma was calculated from change in plasma Na+ concentration. The bicarbonate shift well counterbalanced to the Cl- shift. As the hematocrit was decreased, the amount of CO2 released per mol of hemoglobin increased, while the change in intracellular bound CO2 concentration decreased. That is, the intracellular bound CO2 became higher in the lower hematocrit blood than in the higher hematocrit one. This fact suggested that the intracellular pH became higher as the hematocrit was lowered, and thus the amount of alkali bound with hemoglobin or the CO2 release was enhanced. The Donnan ratio of the bound CO2 at 12 Torr was independent of the hematocrit, though the pH was inversely related to the hematocrit.
D000328:Adult; D002245:Carbon Dioxide / Q000097:blood*; D002463:Cell Membrane Permeability; D004912:Erythrocytes / Q000378:metabolism; D006400:Hematocrit; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D008875:Middle Aged; D010949:Plasma
D002245:Carbon Dioxide