NO CHANGE IN BONE-SPECIFIC ALKALINE-PHOSPHATASE ACTIVITIES IN CULTURED RAT OSTEOBLASTIC CELLS UNDER L-ASCORBATE AND BETA-GLYCEROPHOSPHATE-INDUCED MINERALIZATION

Mineralization occurred both in fetal rat calvarial cells and UMR 106 osteoblastic cells when they were cultured in medium containing L-asco rbate and beta-glycerophosphate as evidenced by von Kossa staining as well as deposition of calcium ions and inorganic phosphate in the cell s. When compared with corresponding non-mineralized cell cultures, bot h the mineralized cultures of calvarial cells and UMR 106 cells did no t exhibit any change in intracellular bone-specific alkaline phosphata se activities which were measured by wheatgerm lectin precipitation me thod. Our results support the hypothesis that mineralization may not e xert any direct negative feedback on matrix protein synthesis in osteo blasts during bone formation.