Hexose transport regulation in cultured hamster cells.

Hamster (nil) cells maintained overnight in culture medium containing cyclohemiximide and either glucose or fructose exhibit strikingly different rates of hexose transport and metabolism (i.e. uptake). Pretreatment of cultures with sulfhydryl reagents makes it possible to determine initial transport rates for a physiological sugar such as galactose which is a catabolite in hamster cells. Using galactose transport as a model, hexose uptake enhancements can now be shown to be due almost entirely to increases in the rate of the transport step. The transport regulation can best be accounted for by a model comprised of 2 antagonizing mechanism. This model involves turnover of transport carriers as well as inhibitory units ("regulators"). The experimental as well as the theoretical model may also apply to the well-known uptake enhancements observed in oncogenically transformed cells.