The chloride shift occurs rapidly and is essentially completes in

Chloride ShiftSince the rise in the HCO3- content of red cells is much greater than that in plasma as the blood passes through the capillaries, about 70% of the HCO3- formed in the red cells enters the plasma.The excess HCO3- leaves the red cells in exchange for Cl-, a process mediated by Band 3, a major membrane protein. This exchange is called the chloride shift. Because of it, the Cl- content of the red cells in venous blood is therefore significantly greater than in aerial blood. The chloride shift occurs rapidly and is essentially completes in 1 second.