Prostaglandin E2 evokes intracellular calcium rise in mouse osteoblastic cell line, MC3T3E-1

The effect of prostaglandin (PG) E2 on the intracellular free calcium concentration ([Ca2+]i) in mouse osteoblastic clone, MC3T3E-1 cells, was investigated with the fluorescent probe fura-2. In the growing phase of MC3T3E-1, PGE2 evoked a transient rise of [Ca2+]i in a dose-dependent manner in the range from 0.28 microM to 5.6 microM of PGE2. The elevation of [Ca2+]i induced by PGE2 was not affected by the presence of EGTA. Moreover, PGE2 (5.6 microM) evoked an acute accumulation of intracellular inositol-1,4,5-trisphosphate (InsP3). The absolute content of InsP3 increased from 5.8 pmole/10(6) cells to 19.2 pmole/10(6) cells within 30 sec after the PGE2 treatment. The degree of [Ca2+]i elevation induced by PGE2 was dependent on the day after subculturing. At day 3, the response to PGE2 was the most pronounced during the 8-day experimental periods. These data suggest that PGE2 evoked a [Ca2+]i rise via a phospholipase C-InsP3 pathway in osteoblasts, particularly in the growing phase.