The exchange of chloride ion (Cl) between the red plood cells and plasma of the toad Bufo Marinus a was studied. In vitro whole blood, plasma and red blood cell samples from the toad were sequentially equilibrated in (1) air, (2) 53 CO₂/air mixture, and (3) air, for 1 h and the Cl⁻ ion concentrations determined. The results showed a significant decrease in plasma cl⁻ concentration and a significant increase in red blood cell Cl⁻ concentration following exposure to 5% CO₂/air mixture, with a return to initial Cl⁻ ion levels following re-equilibration in air. Chloride ion concentration in the whole blood remained constant during the CO₂ equilibration process.
David Ivan Rodenhiser (Sun,) studied this question.