Characterization of the insulinotropic potency of polyunsaturated fatty acids.

In this study we have assessed the individual abilities of the essential fatty acids, linoleic and linolenic acids, to release insulin and compared their insulinotropic potencies with those of the more established nutrient insulin secretagogues, glucose and arginine. In each experiment, a total of six islets microdissected from three mice were preperifused at the rate of 1 ml/min with Krebs-Ringer bicarbonate buffer, pH 7.4, containing 2% bovine albumin and 5.5 mM glucose (basal) with a continuous supply of 95% O2-5% CO2 at 37 C for 1 h. After collecting basal samples, the effects of 27.7 mM glucose, 20 mM arginine, 10 mM linoleic acid (18:2, omega 6), and 5 mM linolenic acid (18:3, omega 3) were tested using a sandwich protocol that entails 20-min alternating periods of stimulation with a secretagogue and a washout with basal perifusion. These nutrient concentrations were selected from initial experiments performed to characterize their dose-response effects on insulin secretion. Effluent samples were co...