Effect of Artificial Carbon Dioxide Bathing on Oxygen-Dissociation Curve of Hemoglobin

Abstract

Many researchers have pointed out that CO₂ bathing directly effects expanding dermal vessels. The authors have recently reported a decrease in red blood cell after CO₂ bathing. To clarify other effects of CO₂ bathing on RBC, the changes in the hemoglobinoxygen-dissociation curve (P50) were measured after single bathing (for 10 minutes at 40°C) with artificial CO₂ water made of sodium bicarbonate and citric acid dissolved in plain water. P50 was measured with an oxygen-dissociation analyzer (HEMO-O-SCAN^TM made by American Instrument Company) and 2, 3-diphosphoglycerate (2, 3-DPG) in RBC, with enzymatic analysis. The subjects of this study consisted of six male patients and four female patients, ranging from 53 to 80 years old.
The results are presented below.
1) Nine of ten patients showed an increase in P50 after 15 to 30 minutes of CO₂ bathing. The remainder showed a transient increase in P50.
2) No significant increase in 2, 3-DPG concentration in RBC was found in the group subjected to CO₂ bathing as compared to that of the controls who were subjected to plain water bathing. However, seven patients showed an increase in 2, 3-DPG after 15 to 30 minutes of CO₂ bathing, and three patients showed a decrease in 2, 3-DPG.
3) Partial pressures of oxygen (PO₂) and carbon dioxide (PCO₂) in the venous blood were measured. Elevation of PO₂, lowering of PCO₂, and increase in pH were observed in almost all patients after a single CO₂ bath.
From these results, we can conclude that a single CO₂ bath effectively decreases oxygen affinity of hemoglobin, presumably due to a rise in the blood temperature and partially due to an increase in 2, 3-DPG concentration in RBC.