This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Diuretic, Subject name: Pharmacology
Amiloride can cause hyperkalemia due to its action on: 
Select and explain. 
A. Potassium channel, B. Sodium channel, C. Na+ Cl- symporter, D. H+K+ATP ase
B: Sodium channel
Answer: B: Sodium channel 
Explanation: Ans. B. Sodium channelAmiloride and triamterene are K+ sparing diuretic, they act by inhibiting epithelial Na+ channel. When they inhibit the sodium channel, there is no generation of electrical gradient and thus potassium and hydrogen are not excreted. They may be responsible for hyperkalemia.