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Zona Glomerulosa Aldosterone — FRCA Primary MCQ

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HardPhysiology - Endocrine & MetabolicZona Glomerulosa AldosteroneFRCA Primary

Primary hyperaldosteronism increases distal sodium reabsorption. Which accompanying tubular effect is most likely in principal cells?

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Correct answer: D — Increased apical ENaC activity and increased potassium secretion

The best answer is “Increased apical ENaC activity and increased potassium secretion”. Aldosterone increases ENaC-mediated sodium entry and basolateral Na+/K+-ATPase activity in principal cells, creating an electrochemical gradient favouring potassium secretion through ROMK. This explains the tendency to hypokalaemia. AQP2 is principally regulated by vasopressin, while SGLT2 is a proximal-tubule transporter.

Reference: RCoA, Primary FRCA syllabus: https://www.rcoa.ac.uk/sites/default/files/documents/2026-01/Primary-FRCA-Syllabus.pdf; Collecting-duct principal-cell transport processes: https://pmc.ncbi.nlm.nih.gov/articles/PMC4284417/