The effect of macrofixation on derepressed sugar transport systems of chick embryo fibroblasts

Abstract

The large molecular weight polyaldehyde (macrofixative) obtained by periodate oxidation of dextran has been shown to react with the external cell surface. Chick embryo fibroblasts (CEF), which had been treated with macrofixative (MFx), were examined for the effect on the rates of sugar transport. The low “basal” rate of sugar uptake, seen in confluent (high density) cultures of CEF was unaffected by such treatment. Low density (rapidly growing) cultures, oncogenically transformed cultures, and glucose-starved cultures have rates of sugar uptake that are significantly higher than the “basal” level. Macrofixation was found to inhibit the induction of higher rate of glucose transport under all of these conditions. The results indicate that a difference may exist between the sugar transport system in resting (confluent) cells, and that in “derepressed” cells.