Spironolactone and eplerenone are potassium-sparing diurectics that inhibit the Na/K ATPase. Na/K ATPase is on the basolateral membrane. None of the answer choices fit with this.
Amiloride and triamterene are also potassium-sparing diuretics. The mechanism is to block ENaC channels on the luminal membrane, this is choice "B."
Should use a potassium-sparing diuretic (FA 591). Triamterene and amiloride work by blocking ENaC channels.
I got that it needed to be a potassium sparing diuretic. Is there a reason it cannot be an aldosterone antagonist? I chose blocks basolateral K+ channels as these decrease the basolateral K+/Na+/ATPase because the wording of the correct answer did not make sense to me -- assuming they were going for an ENaC blocker (and that decreased luminal permeability indicates that Na+ would be remaining in the lumen, not remaining in the principal cell as I originally thought).
It doesn't matter which potassium-sparing diuretic you use. You can still get to this answer. Aldosterone normally upregulates Na/K ATPase in the principal cells of the CD, decreased Na+ intracellularly, which leads to increased ENaC activity. Spironolactone/eplerenone will inhibit this upregulation of ENaC, leading to decreased permeability to Na+ in the CD.
Obv amiloride and triamterene will block principal cell ENaC. It's all in the same class so they will all lead to this effect :)
FA 2019 pg 573
spironolactone and eplerenone are aldosterone receptor antagonist (they block the effect of aldosterone by blocking the basolateral Na/K ATPase pump), this is not the same thing as blocking a basolateral K+ channel. They block and decrease the potassium conduction. There is no basolateral K+ channel
if the (A) were to say "decrease K+ conduction in collecting duct" that might be correct
so (B) is correct. Triamteren and amiloride block Na+ channel on apical (luminal side) side, decrease permeability of Na+