AGE-DEPENDENT CHANGES IN 3-O-METHYLGLUCOSE TRANSPORT IN CHICK-EMBRYO FIBROBLASTS

Transport accross the cell membrane of 3-O-methylglucose, a non-phosphorylatable glucose analogue, was measured in primary cultures of fibroblasts from 8-, 12- and 16-day chick embryos. Transport of this hexose was found to be 3.5 times and 2 times faster in fibroblasts from 16-day embryos than in fibroblasts from 8- and 12-day embryos, respectively. Compared with 8- and 12-day embryos, the rate of efflux in fibroblasts from 16-day embryos was found to be increased. 3-O-methylglucose transport in these cells did not result in an accumulation of the hexose against a concentration gradient. It was concluded that in fibroblasts from older embryos a facilitated diffusion system for hexose transport was stimulated. Embryo differentiation could be associated with a change in the plasma membrane by increasing either the number or the mobility of the glucose carriers, since the Vmax of the transport system for 3-O-methylglucose increased in fibroblasts from older embryos, while the affinity or Km of the system remained unchanged. © 1979.