Glycogen metabolism in human hormone-producing trophoblastic cells in continuous culture. I. Regulation of glycogen metabolism by glucose.

Abstract

Glycogen metabolism was studied in human hormone-producing trophoblastic cells (BeWo line). Cells supplemented daily with high glucose (3 g per liter in medium) contained 5.5% glycogen and utilized glucose at an initial rate of 12.2 mμmoles per min per mg of protein. In cells supplemented daily with low glucose (1 g per liter), the initial rate of glucose consumption was 23 mμmoles per min per mg of protein and the glycogen content reached only 0.4% of wet weight 24 hr after medium replenishment. When glycogen-depleted cultures were refed glucose, an accumulation of glycogen was observed, with initial deposition occurring in areas near the cell surface. After exhaustion of extracellular glucose, cytoplasmic glycogen was utilized at a rate of 2.8 mμmoles per min per mg of protein. Addition of either low or high glucose to glycogen-depleted cells resulted in the same rate of glycogen synthesis (approximately 8 mμmoles per min per mg of protein). It was suggested that unique regulatory mechanisms function in the control of glycogen metabolism in glycoprotein hormone-producing cytotrophoblastic cells.