Claudins in renal physiology and disease

The tight junction forms the paracellular permeability barrier in all epithelia, including the renal tubule. Claudins are a family of tight junction membrane proteins with four transmembrane domains that form the paracellular pore and barrier. Their first extracellular domain appears to be important for determining selectivity. A number of claudin isoforms have been found to be important in renal tubule function, both in adults and in neonates. Familial hypomagnesemic hypercalciuria with nephrocalcinosis is an autosomal recessive syndrome characterized by impaired reabsorption of Mg and Ca in the thick ascending limb of Henle's loop. Mutations in claudin-16 and 19 can both cause this syndrome, but the pathophysiological mechanism remains controversial

Urinary electrolyte monitoring in the critically ill: revisiting renal physiology

The kidney, being one of the most fascinating and commonly studied organs within human physiology, has a crucial role in maintaining the homeostasis of our organism from several different perspectives, from clearing of cellular catabolism products, to body fluids and electrolyte content regulation, hemodynamic stability and acid-base equilibrium [1]. Consequently, despite the existence of many strategies to support its function, the renal system is often the focus of our attention during the clinical management of the critically ill, because its function is frequently altered in this category of patient