Regulation of calcium reabsorption along the rat nephron: a modeling study

panded a mathematical model of transepithelial transport along the rat nephron to include the transport of Ca2 and probe the impact of calcium-sensing mechanisms on Ca2 reabsorption. The model nephron extends from the medullary thick ascending limb (mTAL) to the inner medullary collecting duct (IMCD). Our model reproduces several experimental findings, such as measurements of luminal Ca2 concentrations in cortical tubules, and the effects of furosemide or deletion of the transient receptor potential channel vanilloid subtype 5 (TRPV5) on urinary Ca2 excretion. In vitro microperfusion of rat TAL has demonstrated that activation of the calcium-sensing receptor CaSR lowers the TAL permeability to Ca2, PCaTAL (Loupy A, Ramakrishna