The effects of free fatty acid infusion on glucose metabolism in normal and streptozotocin-treated dogs.

By means of a novel technique for direct intravenous infusion of free fatty acids (FFA) into conscious dogs, it was found that the elevation of FFA levels in normal animals leads to a marked increase in insulin release and to a decrease in plasma glucose concentration. Dogs with streptozotocin-induced diabetes were used for FFA infusion in order to test whether peripheral glucose utilisation would be suppressed by FFA in the absence of the usual insulin response. Diabetic dogs receiving a constant infusion of intravenous glucose were given infusions of oleic acid after control periods of 2-3 hours. Constant intravenous infusion of U-14C-glucose into the diabetic dogs indicated that FFA infusion caused an average transient drop of 36,8% in glucose flux. After 1 1/2 hours of FFA infusion the flux returned to the former rates. Because no change in plasma glucose levels was found during FFA infusion our results can be explained only by a drop in hepatic glucose production concomitant with an equal drop in peripheral glucose utilisation.