Calcium fluxes at the bone/plasma interface: Acute effects of parathyroid hormone (PTH) and targeted deletion of PTH/PTH-related peptide (PTHrP) receptor in the osteocytes.

Calcium ion concentration ([Ca]) in the systemic extracellular fluid, ECF-[Ca], is maintained around a genetically predetermined set-point, which combines the operational level of the kidney and bone/ECF interfaces. The ECF-[Ca] is maintained within a narrow oscillation range by the regulatory action of Parathyroid Hormone (PTH), Calcitonin, FGF-23, and 1,25(OH)D. This model implies two correction mechanisms, i.