Sodium-potassium-chloride symporter 2 (NKCC2)

The **sodium-potassium-chloride symporter 2** (NKCC2, encoded by the SLC12A1 gene) is a membrane transporter protein predominantly expressed in the thick ascending limb of the loop of Henle in the kidney[1][6][7]. It mediates the **coupled, electroneutral transport of sodium, potassium, and chloride ions from the tubular lumen into renal epithelial cells** (with a stoichiometry of 1 Na^+, 1 K^+, 2 Cl^−), playing a crucial role in salt reabsorption, urine concentration, and systemic electrolyte balance[1][6]. NKCC2 function is essential for the kidney's ability to generate a concentrated urine and maintain extracellular fluid osmolarity. It is a validated **therapeutic target for loop diuretic drugs** such as furosemide and bumetanide, which inhibit its activity to induce natriuresis and diuresis for the treatment of edema and hypertension[1][6]. Loss-of-function mutations in SLC12A1 cause Bartter syndrome type I, a hereditary salt-losing tubulopathy[6]. NKCC2 belongs to the cation-coupled chloride cotransporter family, and its regulation is modulated by phosphorylation, membrane trafficking, and various hormonal signals[6][2].

Other names

Na-K-2Cl cotransporter 2Na^+-K^+-2Cl^− cotransporter 2NKCC2Solute carrier family 12 member 1SLC12A1

Inhibition of sodium-potassium-chloride transport (diuretics: loop diuretics inhibit NKCC2, leading to increased excretion of Na^+, K^+, and Cl^−) Blockade of ion reabsorption in the thick ascending limb of the loop of Henle