Cyclo-oxygenase products of arachidonic acid metabolism in rat osteoblasts in culture

Abstract

The metabolism of arachidonic acid to its cyclo-oxygenase products was studied in monolayer cultures of osteoblast-rich rat calvarial cells and of clonal cell lines from a rat osteogenic sarcoma, enriched in the osteoblast phenotype. Prostanoids were measured by radioimmunoassay after extraction of media and fractionation by high pressure liquid chromatography. In both normal and malignant osteoblasts the major cyclo-oxygenase product was 6-oxo-prostaglandin F_1α, the hydration product of prostacyclin, with lesser amounts of prostaglandin E₂ and prostaglandin F_2α. No significant thromboxane B₂ was detected. Prostaglandins are thought to have a local role in the regulation of bone resorption. These results point to the possible importance of prostacyclin either in bone resorption or in some other local function, e.g., regulation of bone blood flow.