ADH acts on the principal cells of the collecting duct to increase water reabsorption. Which intracellular sequence correctly describes this action?

• A Binding to V1 receptor, activation of phospholipase C, calcium release
• B Direct diffusion of ADH into the cell and transcription of the Na-K-2Cl cotransporter
• C Binding to V2 receptor, activation of phospholipase A2, prostaglandin-mediated water transport
• D Binding to V2 receptor, increase in cAMP, insertion of aquaporin-2 into the apical membrane ✓

Explanation

ADH binds the V2 receptor on the basolateral membrane of collecting duct principal cells, a Gs-coupled receptor that raises intracellular cAMP. Protein kinase A then triggers trafficking of preformed aquaporin-2 channels into the apical membrane, allowing water to follow the medullary osmotic gradient. Option A describes the V1 pathway, which mediates vasoconstriction in vascular smooth muscle through calcium, not renal water handling.

Reference: Guyton and Hall Textbook of Medical Physiology, 14th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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