2009 Homer W. Smith Award: Minerals in Motion: From New Ion Transporters to New Concepts

The kidneys play a critical role in maintaining the systemic balance of Mg(2+) and Ca(2+) cations. The reabsorptive capacity of these divalent cations adapt to changes in their plasma concentrations Active reabsorption of Mg(2+) and Ca(2+) takes place in the distal convoluted and connecting tubules, respectively, and is initiated by cellular transport through selective transient receptor potential (TRP) channels located along the luminal membrane and modulated by hormonal stimuli. Recent characterization of underlying molecular defects in renal Mg(2+) handling illuminate complex transport processes in the kidney and their contribution to the overall mineral balance. Likewise, studies of Ca(2+) transport proteins in null mice disclose molecular mechanisms maintaining normal plasma Ca(2+) levels and the hypercalciuria-related adaptations important in the prevention of kidney stones. Current knowledge of Mg(2+) and Ca(2+) transport is summarized here as comprehensive cellular models of the distal nephron.