Effect of age on calcium release from mouse calvaria in tissue culture

The effect of age on calcium release in organ culture was studied using calvaria from 5-, 14-, 30-, and 75-day-old mice. The results demonstrated a different and characteristic calcium release pattern over the 14-day culture period for untreated calvaria of different ages. Since calcium release in all cultures was abolished by procedures such as boiling, multiple freezing and thawing, maintaining cultures in an oxygen-free gas phase, or maintaining cultures in a non-nutritive medium, it was concluded that the calcium release from older calvaria was due to a cell-mediated process. Histological observations demonstrating the presence of Howship's lacunae and active osteoclastic resorption confirmed that calcium release from older calvaria was due to an active bone resorption process. Parathyroid hormone did not substantially alter the general pattern of calcium release exhibited by different aged calvaria. However, it tended to exaggerate the magnitude of the response. Indomethacin and dexamethasone inhibited calcium release from untreated 5- and 75-day-old calvaria suggesting that prostaglandin biosynthesis was involved in the calcium release process. Direct measurements of PGE2 and PGI2 released into the culture medium gave results consistent with this hypothesis, although it is conceivable that indomethacin and dexamethasone might have influenced calcium release by other mechanisms.