DIFFERENTIAL-EFFECTS OF SODIUM-BUTYRATE AND HYPEROSMOLALITY ON THE MODULATION OF ALKALINE-PHOSPHATASES OF LOVO CELLS

LoVo cells produce term-placental and intestinal alkaline phosphatases. Hyperosmolality and sodium butyrate increase the levels of both, but the effect of sodium butyrate is more pronounced on the intestinal enzyme. When applied together, induction of term-placental alkaline phosphatase is additive and that of the intestinal enzyme is synergistic. Induction by either stimulus or by their mixture is independent of cell density. However, whereas the effect of hyperosmolality is readily reversible, induction by sodium butyrate is not. No synergistic increase in intestinal alkaline phosphatase activity occurs when cells are sequentially treated with hyperosmolality and sodium butyrate or vice versa. This indicates that only when applied concurrently does one inducer amplify the effect of the other. Since the normal colonic mucosa produces intestinal alkaline phosphatase, its predominant induction by sodium butyrate in LoVo cells may reflect a more differentiated state. © 1990.