Diabetes, Vol 40, Issue 6 783-786, Copyright © 1991 by American Diabetes Association
Prevention of inhibitory effect of free fatty acids on insulin binding and action in isolated rat hepatocytes by etomoxir
J Svedberg, P Bjorntorp, P Lonnroth and U Smith
Department of Medicine, University of Goteborg, Sweden.
We recently demonstrated a marked inhibitory effect of high physiological
concentrations of free fatty acids (FFAs) on insulin binding, degradation,
and action in isolated rat hepatocytes. To elucidate the mechanism, male
rats were treated for 3 days with saline (control) or etomoxir (ethyl
2-[6-(p-chlorophenoxy)hexyl]-glycidate), a prodrug, which in vivo is
converted to a specific competitive inhibitor of carnitine
palmitoyltransferase, and thus, lipid oxidation. Oleic acid (0.4 mM)
reduced both 125-I-labeled insulin binding and insulin-stimulated
[14C]aminoisobutyric acid transport approximately 40% in cells from control
animals. However, this FFA concentration was without effect in cells from
etomoxir-treated animals. Etomoxir increased EC50 for the inhibitory effect
of oleic acid on insulin binding approximately threefold. The data indicate
that the mitochondrial oxidation of fatty acids may be important for their
inhibitory effect on insulin binding and action in isolated rat
hepatocytes.