The distal nephron is able to fine-tune sodium and water balance because it can regulate reabsorption of sodium and water independently of each other. This is unlike the proximal nephron, where an increase in sodium reabsorption will lead to an increase in water reabsorption due to the creation of an osmotic gradient and free permeability to both sodium and water. How does vasopressin affect water reabsorption in the distal nephron in response to a negative water balance?
A. Increased circulating vasopressin increases expression of aquaporin on the luminal membrane.
B. Increased circulating vasopressin decreases expression of aquaporin on the luminal membrane.
C. Decreased circulating vasopressin increases expression of aquaporin on the luminal membrane.
D. Decreased circulating vasopressin decreases expression of aquaporin on the luminal membrane.