Final answer:
Aldosterone stimulates principal cells to manufacture channels and pumps that regulate the recovery and secretion of sodium and potassium. When aldosterone levels increase, more sodium is recovered from the urine and more potassium is secreted.
Step-by-step explanation:
Aldosterone stimulates principal cells to manufacture luminal Na+ and K+ channels as well as Na/K+ ATPase pumps on the basal membrane of the cells. When aldosterone output increases, more Na+ is recovered from the forming urine and water follows passively. As the pump recovers Na+ for the body, it also pumps K+ into the forming urine, since the pump moves K+ in the opposite direction. When aldosterone decreases, more Na+ remains in the forming urine and more K+ is recovered in the circulation.
Symport channels move Na+ and Cl- together. Still other channels in the principal cells secrete K+ into the collecting duct in direct proportion to the recovery of Na+.