Physiology Which of the following is the mode of action of vasopressin? A Facilitates water absorption at medullary ducts B Increasing permeability of H2O across collecting duct C Facilitate water absorption at PCT D Facilitate H2O secretion at loop of henle 💡 Explanation Which of the following is the mode of action of vasopressin? ✓ Correct Answer: B. Increasing permeability of H2O across collecting duct