CASR and Hypercalciuria: Another Bartter-like syndrome is produced by activating mutations of the calcium sensing receptor (CaSR).34,35 When extracellular calcium raises, the activation of the Gαq CaSR in the basolateral membrane of the TAL (Figure 1), reduces the activity of the Na-K-2Cl, NKCC2 and the apical K+ channel, ROMK, to reduce the intraluminal positive voltage that drives the Ca2+ reabsorption trough the paracellular pathway (Figure 1), thus inducing hypercalciuria.