The effect of digitonin of the stimulation by insulin of glucose uptake by isolated fat cells.

The effect of digitonin on glucose uptake by isolated fat cells in the presence and absence of insulin has been studied. At low concentrations of digitonin, the stimulation of glucose uptake by insulin was inhibited without severe cell damage as estimated by the leakage of lactate dehydrogenase from the cells. The inhibition of the insulin effect was not reversed by washing the cells or by the addition of cholesterol or lecithin-cholesterol liposomes to the incubation medium of the cells after treatment with digitonin. Cholesterol was shown to be present in the fat cells and it is suggested that the inhibition of the insulin effect is a consequence of the formation of digitonin-cholesterol complexes in the fat cell plasma membrane. Possible ways in which this may results in inhibition of the effect of insulin are discussed.