All of the following diuretics inhibit Na+-K+-2Cl- symporter, except:
**Core Concept**
The Na+-K+-2Cl- symporter is a cotransporter responsible for the reabsorption of sodium, potassium, and chloride ions in the thick ascending limb of the loop of Henle in the kidneys. Inhibiting this symporter leads to increased excretion of these ions, resulting in a potent diuretic effect.
**Why the Correct Answer is Right**
Loop diuretics, such as furosemide and bumetanide, work by inhibiting the Na+-K+-2Cl- symporter in the thick ascending limb of the loop of Henle. This inhibition leads to a decrease in sodium, potassium, and chloride reabsorption, resulting in increased excretion of these ions and a diuretic effect. The mechanism of action involves the inhibition of the symporter, which is responsible for the reabsorption of these ions.
**Why Each Wrong Option is Incorrect**
**Option A:** Thiazide diuretics, such as hydrochlorothiazide, work by inhibiting the Na+-Cl- cotransporter in the distal convoluted tubule, not the Na+-K+-2Cl- symporter.
**Option B:** Metolazone is a thiazide-like diuretic that also works by inhibiting the Na+-Cl- cotransporter, not the Na+-K+-2Cl- symporter.
**Option C:** Torsemide is a loop diuretic that works by inhibiting the Na+-K+-2Cl- symporter in the thick ascending limb of the loop of Henle, similar to furosemide and bumetanide.
**Clinical Pearl / High-Yield Fact**
Loop diuretics are often used in the treatment of edema, hypertension, and congestive heart failure. They are also used to treat conditions such as glaucoma and ascites.
**Correct Answer:** D.