Chapter 07, Phosphate Homeostasis Regulatory Mechanisms

By Francis Glorieux

Academic Press
Publication date: September 2011

ISBN: 9780124094017

Digital Book format: ePub (Adobe DRM)

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This chapter reviews the physiology of Pi homeostasis and the regulatory mechanisms. A major function of bone is to provide mechanical support for the entire body. This is achieved by mineralization of an extracellular matrix, which is formed by osteogenic cells and comprises Pi as an integral component of hydroxyapatite crystals. Pi also affects the function of chondrocytes, osteoblasts, osteocytes, and osteoclasts, thereby modifying the rate of bone growth; matrix production and bone resorption plasma Pi concentration is higher in growing individuals than in adults, most likely to accommodate the increased requirement for Pi during growth and skeletal development. Osteoclasts, the bone-resorbing cells, are exposed to high ambient Pi concentrations during the active resorptive process. Their precursors are derived from monocyte-macrophage lineage cells, which require macrophage colony-stimulating factor (M-CSF) and physical contact with bone-forming osteoblasts for differentiation into mature bone-resorbing osteoclasts.