Alkaline Phosphatase Modulation by Osmolality Changes During the Growth Cycle of KB Cell Cultures 1

Summary

Growing KB cells in hyper-osmolar medium causes a reduction in total alkaline phosphatase activity associated with a decrease in the proportion of the heat-labile and an increase of the heat-stable enzyme components. In standard medium enzyme activity increases progressively during a 6-day growth cycle and the proportion of heat-stable activity remains constant. In hyperosmolar medium, activity increases only during the initial 24 hr after the change in osmolality and then levels off, but the heat-stable alkaline phosphatase activity increases 7-fold within 48 hr. The transition in thermostability is discernible 24 hr after increasing the osmolality of the medium and toward the end of a growth cycle most of the activity is heat-stable.