Fig. 4.

With no lysine kinase (WNK) bodies appear in morphologically normal tubules. A: antibody against residues 367–379 of human Ste20-related proline-alanine-rich kinase (SPAK) phosphorylated on Ser373 (pS373-SPAK) displays a punctate signal in hypokalemic patients, shown here in a distal convoluted tubule (DCT) with normal morphology as visualized by differential interference contrast optics. Na⁺-Cl⁻ cotransporter (NCC) locates to the luminal DCT membrane in the biopsies of patients with hypokalemia and control biopsies. B–D: renal cortex of both patients with hypokalemia (B and C) and a control needle biopsy (D). Periodic acid-Schiff stain, ×400 magnification with regions of interest containing DCTs at ×1,000 magnification. In both patients with hypokalemia, the DCTs that have not been affected by vacuolization display morphology comparable to that of the control. CnI, calcineurin inhibitors.