Osteocytes and calcium homeostasis

Osteocytes link bone maintenance to blood homeostasis.

O steocytes are the most abundant cell type in the bone, comprising more than 90% of all cells within the bone matrix or on bone surfaces. Osteocytes are derived from osteoblasts and are entombed in the bone matrix during bone deposition. Osteocytes were originally thought to be rather inert cells whose function was limited to maintaining bone matrix locally. However, osteocytes are connected t...

Regulation of Bone Homeostasis by Osteocytes.

New data concerning the function of osteocytes as the central regulators of bone homeostasis are briefly outlined. It is established that osteocytes are the main target cells for parathormone. They are a rich source of sclerostin, the main inhibitor of osteoblast activity, and of the RANKL cytokine, the most important regulator of osteoclastogenesis. Under shear stress causing microinjury, oste...

ANTICONVULSANT THERAPY-INDUCED ALTERATIONS IN CALCIUM HOMEOSTASIS

35 epileptic patients, aged 10 to 58 years (mean 23), who were taking anticonvulsant drugs were studied. The patients exhibited a 34% reduction in serum calcium levels, a 41 % increase in serum alkaline phosphatase activity and a slight but insignificant decrease in serum phosphate, compared to untreated controls. These changes appear to be related to the anticonvulsant drug taken, in the ...

Kidney and Calcium Homeostasis

Plasma calcium concentration is maintained within a narrow range (8.5-10.5 mg/dL) by the coordinated action of parathyroid hormone (PTH), 1,25(OH)2D3, calcitonin, and ionized calcium (iCa(2+)) itself. The kidney plays a key role in this process by the fine regulation of calcium excretion. More than 95% of filtered calcium is reabsorbed along the renal tubules. In the proximal tubules, 60% of fi...

Calcium and Magnesium Homeostasis