Sex differences in insulin action on glucose transport and transporters in human omental adipocytes.

We examined the effects of insulin on glucose transport and subcellular glucose transporter distribution in isolated omental adipose cells from men and women. 3-O-Methylglucose transport was measured in intact cells, and the number of glucose transporters in plasma membranes and low density microsomal membranes was determined using the cytochalasin B binding assay. Compared to adipocytes from women, omental adipocytes from men were characterized by 1) 2-fold larger cell volume; 2) 4- to 5- and 2.5-fold higher glucose transport rates when calculated per cell or per cell surface area, respectively, in either basal or insulin-stimulated cells; 3) similar 2-fold insulin stimulating effect per se; and 4) equal concentrations of transporters in both fractions examined, but a 2-fold increase in their total number per cell. Additionally, although not directly measured, the calculated glucose transporter activity in basal plasma membranes prepared from adipocytes from men was 2.7-fold higher than that in women, an...