The effect of carbon dioxide and h⁺ on canine erythrocyte glycolysis

Incubation of canine erythrocytes in 0.5% CO₂, in air or 5% CO₂ has no significant effect on glucose utilization if pH is constant. Decreasing pH from 7.7 to 7.2 decreased glucose utilization at a given concentration of CO₂. At a given pH decreasing CO₂ from 5% to 0.5% increased lactate production. Decreasing pH from 7.7 to 7.3 reduced potassium uptake by erythrocytes and decreasing CO₂ from 5% to 0.5% decreased uptake further, so that net output was observed at pH 7.2, CO₂ 0.5%. These findings are consistent with a pH effect upon glucose utilization probably at the phosphofructokinase step. These data are suggestive of a second control step responsive to CO₂ which lies distal to the pH effect. The effect of CO₂ on potassium flux probably represents an alteration in erythrocyte energy metabolism with decrease energy availability. Hydrogen ion and CO₂ control of erythrocyte metabolism could act to alter haemoglobin affinity for oxygen and carbon dioxide and hence act as a physiologic signal system.