Effects of Oleate and Insulin on Glucose Uptake, Oxidation, and Glucose Transporter Proteins in Rat Adipocytes

We examined effects of Na oleate on glucose uptake, glucose transporter protein concentrations, and glucose oxidation in isolated adipocytes from fed rats. Na oleate increased basal ¹⁴C-glucose uptake in a dose-dependent manner (+42% with 1.0 mM, +79% with 2.8 mM Na oleate), but had no statistically significant effect on insulin-stimulated glucose uptake. Insulin (100 nM) resulted in a redistribution of GLUT4 protein concentration from the LDM fraction (−42%) to the PM fraction (+266%) but did not affect the distribution of GLUT1. Na oleate had no effect on basal or insulin-stimulated concentrations of GLUT1 or GLUT4 proteins in the PM or LOM fractions. Na oleate (2.8 mM) had no statistically significant effect on basal glucose oxidation, but inhibited insulin-stimulated glucose oxidation by 48% (P < 0.01). In summary, Na oleate inhibited insulin-stimulated glucose oxidation and stimulated basal glucose uptake in isolated adipocytes without affecting PM or LDM distribution of GLUT1 or GLUT4 proteins. We conclude that the stimulatory effect of Na oleate on basal glucose uptake in adipocytes may be mediated by changes in the intrinsic activity of the glucose transporters.