Source of plasma free fatty acids in dogs receiving fat emulsion and heparin

¹ Departments of Physiology and Pharmacology, Vanderbilt University Medical School, Nashville, Tennessee, and Karolinska Institute, Stockholm, Sweden

Unanesthetized dogs were given either 3.0 g fat/kg as a 20% fat emulsion or heparin (2 mg/kg) intravenously or both. Plasma free fatty acids (FFA) and lipolytic activity were determined at intervals. In some experiments hexamethonium (5 mg/kg), a sympathetic ganglionic blocking agent, was administered intravenously either before or after fat or heparin. In fasting dogs fat infusion produced a moderate and heparin caused a slight rise in plasma FFA. Heparin given during lipemia produced a marked elevation of plasma FFA. The plasma lipolytic activity was increased after fat emulsion or heparin. Hexamethonium reduced the fasting plasma FFA about 70% or 0.40–0.6 mEq/liter. A similar reduction of plasma FFA also was observed when hexamethonium was administered during fat infusion or after heparin. Hexamethonium did not affect the increase in plasma lipolytic activity following the administration of fat emulsion or heparin. It seems probable that the increase in plasma FFA observed after intravenous infusion of fat emulsion or heparin is mainly due to the result of intravascular lipolysis.