Perturbation of the adipose cell plasma membrane in obese (ob/ob) mice.

The plasma membrane organization of adipocytes of genetically obese (ob/ob) mice has been studied by freeze-fracture and compared to that of control (lean) mice and of small and large adipocytes in rats of different age. The large size increase of ob/ob adipocytes is accompanied by a decrease in the concentration of surface invaginations and of intramembrane particles in the plasma membrane as compareed to control, nonobese mice. By contrast, the membrane of large adipocytes of normal old rats has a concentration of invaginations and particles similar to that present in the membrane of small adipocytes of young rats. Thus, the changes of the plasma membrane organization in ob/ob adipocytes seems not to be due to size increase only but may reflect a more general perturbation of the membrane, such as evidenced by the reduced insulin and lectin binding capacity demonstrated in these cells.