Figure 1215

Proposed pathogenic model for the antenatal and classic variants of Bartter's syndrome. Genetic studies have identified mutations in the genes encoding the bumetanide-sensitive sodium-potassium-2chloride cotransporter (NKCC2), luminal ATP-regulated potassium channel (ROMK), and kidney-specific chloride channel (ClC-K2). These findings support the theory of a primary defect in thick ascending limb (TAL) sodium-chloride (Na-Cl) reabsorption in, at least, subsets of patients with the antenatal or classic variants of Bartter's syndrome. In the proposed model the potential interrelationships of the complex set of pathophysiologic phenomena are illustrated. The resulting clinical manifestations are highlighted in boxes [25]. Ca2+— calcium ion; H+—hydrogen ion; K+—potas-sium ion; Mg2+—magnesium ion; PGE2— prostaglandin E2.

Gene defect Pathophysiologic model

Defective NCCT

Defective NaCl ttansport in DCT

Volume contraction

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