Plasma free fatty acid turnover during insulin-induced hypoglycemia

¹ Department of Biology, Brookhaven National Laboratory, Upton, New York; and Department of Pharmacology, New York University School of Medicine, New York City

Plasma free fatty acid (FFA) concentration falls when an infusion of glucagon-free insulin is initiated in the normal unanesthetized dog in the postabsorptive state. Using C¹⁴ palmitate it was shown that the lowered FFA concentration is caused by decreased FFA production. This decreased FFA production accompanies increased glucose uptake by the tissues as demonstrated using C¹⁴ glucose. During slow insulin infusion, when plasma glucose concentration remains above 75 mg%, FFA production and concentration remain low. However, during more rapid insulin infusion, when plasma glucose concentration falls below 50 mg%, the initially lowered FFA production rebounds and FFA production and concentration exceed the preinsulin level. Glucose uptake always remains elevated during insulin infusion. Dibenzyline or guanethidine pretreatment blocks the rebound in FFA production. Thus decreased FFA production, due presumably to decreased FFA release by adipose tissue because of insulin-stimulated glucose uptake, can be overpowered by a sympatho-adrenal response to hypoglycemia during a continued infusion of insulin and a resulting continued increased glucose uptake.

Note:
With the Technical Assistance of C. Bjerknes