Claudins Mediate Specific Paracellular Fluxes in Vivo: Paracellin-1 Is Required for Paracellular Mg2+ Flux

Homeostasis .........................................................................484 22.3 Recessive Renal Hypomagnesemia with Hypercalciuria and

Nephrocalcinosis .........................................................................................486 22.4 Positional Cloning of the Gene Causing Recessive Renal

Hypomagnesemia........................................................................................487 22.5 Paracellin-1 and Paracellular “Channels” ..................................................489 22.6 Conclusion ..................................................................................................491 References..............................................................................................................491

Epithelial layers constitute barriers that maintain distinct compositions of the fluids on their apical and basolateral aspects. Nonetheless, an important role of epithelia