Evidence for intermediate channelling in the glycolytic pathway of permeabilized L-929 cells

L-929 cells permeabilized by dextran sulfate (DSP cells) carry out vigorous and linear rates of glycolysis when supplied with a suitable incubation medium. Unlabeled 3-phosphoglycerate (PGA) added to DSP cells reduces the specific activity of lactate coming from [14C]glucose but the extent of this reduction can not be accounted for on the basis of free diffusion of PGA coming from [14C]glucose. Studies on other glycolytic intermediates, although preliminary, yield similar results. PGA also inhibits the production of lactate from glucose; however, this effect, like that of the reduction of lactate specific activity, becomes apparent only at concentrations of PGA well in excess of those considered to be physiological. We conclude that channelling of PGA, and probably other intermediates, occurs but is of the "leaky" type.