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

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 cyclooxygenase product was 6-oxo-prostaglandin F1 alpha, the hydration product of prostacyclin, with lesser amounts of prostaglandin E2 and prostaglandin F2 alpha. 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.