The Effect of Membrane Phospholipid Modification on Insulin Action in Adipocytes from Normal and Streptozotocin-Induced Diabetic Rats

Abstract

The effects of membrane phospholipid modification on insulin-stimulated hexose transport and antilipolysis was studied in isolated adipocytes derived from normal and streptozotocin (STZ)-diabetic rats. The marked inhibition of glucose transport observed in normal adipocytes pretreated with phospholipid vesicles composed of dioleoylphosphatidylcholine and phosphatidylserine (DOPC-PC) was not apparent in cells from diabetic animals. Inhibition of glucose oxidation in cells from non-diabetic, but not diabetic rats, was also detected under conditions where transport rate was insufficient to saturate the intracellular processes leading to oxidation. The antilipolytic effect of insulin, on the other hand, was not significantly impaired by vesicle pretreatment of cells from either the control or diabetic animals. These studies suggest that vesicles may have a specific effect on the glucose transport system and that changes in responsiveness of insulin-stimulated glucose transport may be related to alterations of membrane phospholipids.