Inhibition of A23187-stimulated bone resorption in tissue culture by serum and indomethacin.

The present study addresses the controversy that currently exists concerning the effect of the divalent cation ionophore A23187 on bone resorption in tissue culture. We show here that this compound is ineffective if serum is present in the culture medium. However, in a serum-free medium it effectively stimulates bone resorption in neonatal mouse calvaria cultures. This finding does account for the various conflicting reports in the literature. Furthermore, the stimulation of bone resorption by the ionophore was accompanied by increased prostaglandin E2 production. Indomethacin inhibited both phenomena, indicating that prostaglandin E2 biosynthesis is involved in mediating the bone resorption-stimulating effect of A23187.