High concentration of glucitol in fetal serum and glucitol permeable cells

We found that the glucitol concentration was extraordinarily high in bovine fetal serum, which is routinely used for cell culture in laboratories: it was as much as two orders of magnitude higher than that reported for human adult serum. We also confirmed that the serum glucitol concentration in new born babies was on average 5.5-fold higher than in the maternal serum. These observations raise the possibility that some tissue(s) demand extracellular glucitol during embryogenesis and this indicates that the cells in such tissues could be permeable to glucitol. Since the hepatic metabolism of glucitol had been reported, we investigated glucitol permeability and its metabolism in rat hepatoma cells, Reuber H-35. The cells rapidly incorporated glucitol but the mode of incorporation was unusual: the incorporation rate was still proportional to the ambient glucitol concentration at 100 mM. The major part of the incorporated glucitol underwent metabolic conversion to probably negatively charged metabolites. Active synthesis of glucitol was also observed in the same cells. The cells proliferated normally in medium containing glucitol instead of glucose. This observation may indicate that glucitol can substitute for glucose in the culture of H-35 cells.