H(+)-stimulated release of prostaglandin E2 and cyclic adenosine 3',5'-monophosphoric acid and their relationship to bone resorption in neonatal mouse calvaria cultures.

The addition of protons to the medium of neonatal mouse calvaria cultures stimulated bone resorption and release of calcium into the medium. In addition, added protons significantly increased the release of prostaglandin E2 (PGE2) and cyclic adenosine 3',5'-monophosphoric acid (cAMP) from the bones. Indomethacin significantly inhibited the release of calcium, PGE2 and cAMP from proton-treated cultures. The positive control, parathyroid hormone (PTH)-treated cultures, also gave rise to bone resorption and calcium release into the medium. However, unlike the addition of protons, the addition of PTH did not stimulate PGE2 release nor did indomethacin inhibit calcium release from PTH-treated cultures. In addition, indomethacin only slightly inhibited cAMP release from PTH-treated cultures, as compared to the marked inhibition by indomethacin of cAMP release from proton-treated cultures. These findings indicate that bone resorption due to added protons is dependent on both PGE2 and cAMP production, whereas bone resorption due to PTH only involves cAMP production.