Regulation of intestinal calcium transport

Calcium is an essential ion in all organisms and participates in a variety of structural and functional roles. Calcium (re)absorption occurs in epithelia, including the intestine, kidney, mammary glands, placenta, and gills of fish. Its transport is regulated by a complex array of processes that are mediated by hormonal, developmental, and physiological factors involving the gastrointestinal tract, bone, kidney, and the parathyroids. Here we review the calcium transport mechanisms-paracellular, which is energy independent, and transcellular, which is energy dependent-primarily focusing oil the intestine. We provide a new perspective oil the facilitated diffusion and vesicular transport models to account for the emerging concepts oil transcellular calcium transport. Finally, we discuss how 1,25(OH)(2)D-3 and parathyroid hormone regulate calcium transport.