Apoptosis of growth plate chondrocytes occurs through a mitochondrial pathway

Objective: To determine the role of mitochondria in chondrocyte apoptosis induced by inorganic phosphate (Pi). Materials and Methods: Chondrocytes isolated from the growth plates of chick embryo tibia were treated with Pi in serum-free media; chondrocyte viability, mitochondrial membrane potential, cytochrome c release from mitochondria, caspase 3 activity, endonuclease activity, and DNA fragmentation were investigated. Results: Exposure to Pi for 24 hours induced apoptosis in growth plate chondrocytes through a pathway that involved loss of mitochondrial function, release of cytochrome c into the cytoplasm, increases in caspase 3 and endonuclease activities, and fragmentation of DNA. Conclusions: This study suggests that mitochondria are important players in Pi-induced apoptosis.