Synergistic stimulation of alkaline phosphatase activity in bovine aortic endothelial cells grown in the presence of retinoids and glucocorticoids.

Low concentrations of retinol (10 nM-10 microM) and dexamethasone (0.1 nM-1.0 microM) elevated activity of alkaline phosphatase (E.C. 3.1.3.1) in bovine endothelial cells in culture. The effect was apparent after 48 hr of growth in the presence of either of the two compounds, prior to any growth stimulatory effects. A synergistic stimulation of alkaline phosphatase was achieved in the presence of both retinol and dexamethasone implying different mechanisms of induction. Retinoic acid and retinyl acetate also elevated alkaline phosphatase but the retinol analogue reduced in the side chain (perhydroretinol) was inactive. The ability of steroids to elevate alkaline phosphatase activity was associated with the structure commonly required for glucocorticoid activity; however, competitors for the steroid receptor binding failed to prevent the elevation by dexamethasone or the synergism in the presence of retinol and dexamethasone.