Fig. 7.

Model of PGT facilitated enhanced prostaglandin E₂ (PGE₂) stimulation of Na⁺ and water excretion. Upon sodium loading, cyclooxygenase-2 in kidney is induced resulting in more PGE₂. The PGE₂ level is increased on both luminal and basolateral sides of the collecting duct. PGT is located on the luminal side of the collecting duct. Upon salt loading, PGT is also increased and takes up more luminal PGE₂ into the principal cells. The concentrated PGE₂ in the principal cells diffuses into the basolateral side of collecting duct and stimulates Na⁺ and water excretion by interacting with its basolateral receptors EP₁ and EP₃.