Spironolactone and Triamterene act on which parts of the nephron to conserve potassium?

Spironolactone and Triamterene act on which parts of the nephron to conserve potassium?

• A. Proximal tubule and loop of Henle
• B. Distal convoluted tubule and collecting duct
• C. Bowman's capsule
• D. Papillary duct

Answer: (B)

Potassium handling in the kidney is finely controlled in the distal nephron, especially the late distal tubule (distal convoluted tubule) and the collecting duct. Spironolactone and triage drugs act here to conserve potassium. Spironolactone blocks aldosterone receptors in the principal cells of the collecting duct, which reduces the expression and activity of sodium channels and related pumps. With less Na+ reabsorption, the driving force for K+ secretion into the tubular lumen decreases, so less potassium is lost in urine. Triamterene directly blocks the epithelial sodium channels (ENaC) in the same distal segments, again lowering Na+ uptake and the lumen-negative potential that promotes K+ secretion. Together, both drugs reduce potassium wasting by acting in the distal convoluted tubule and collecting duct. Bowman's capsule and the papillary duct are not the primary sites where this potassium-sparing action occurs.

Potassium handling in the kidney is finely controlled in the distal nephron, especially the late distal tubule (distal convoluted tubule) and the collecting duct. Spironolactone and triage drugs act here to conserve potassium. Spironolactone blocks aldosterone receptors in the principal cells of the collecting duct, which reduces the expression and activity of sodium channels and related pumps. With less Na+ reabsorption, the driving force for K+ secretion into the tubular lumen decreases, so less potassium is lost in urine. Triamterene directly blocks the epithelial sodium channels (ENaC) in the same distal segments, again lowering Na+ uptake and the lumen-negative potential that promotes K+ secretion. Together, both drugs reduce potassium wasting by acting in the distal convoluted tubule and collecting duct. Bowman's capsule and the papillary duct are not the primary sites where this potassium-sparing action occurs.