Question

There are a number of drugs that, as a side effect, interfere with the function of the bicarbonate chloride anion exchanger in red blood cells. What is the function of this anion exchanger and what are some potential consequences to gas transport if its function is reduced? Explain your answer.

Answer 1

The net direction of bicarbonate-chloride exchange (bicarbonate out of RBCs in the systemic capillaries, bicarbonate into RBCs at pulmonary capillaries) proceeds in the direction that decreases the sum of the electrochemical potentials for the chloride and bicarbonate ions being transported. In the lungs, bicarbonate is transported back into the red blood cells in exchange for chloride. The H+ dissociates from haemoglobin and combines with bicarbonate to form carbonic acid with the help of carbonic anhydrase, which further catalyzes the reaction to convert carbonic acid back into carbon dioxide and water. This is the major pathway by which CO2 is transported out of the blood. Thus if its function is reduced CO2 transport will be affected and it will be accumulated in the blood.