Method for continuous intravenous infusion of large amounts of oleic acid into rats.

A method has been developed for the continuous intravenous infusion of large amounts of oleic acid into rats. The acid was infused in the form of an emulsion prepared by sonication and stabilized with albumin in low concentration. Fatty acid was infused at a rate equal to the turnover rate of endogenous free fatty acids and the infusion was continued for 3 hr. During this time there was no evidence of hemolysis or hemoglobinuria; only on occasion did a small clot form at the tip of the infusion catheter. The infused fatty acids became attached to the circulating albumin and were removed from the plasma and metabolized in the same way as endogenous free fatty acids. There was no evidence to indicate that the infused fatty acids lodged as emboli in the microcirculation or were phagocytized by the reticuloendothelial system. This method makes it possible to study the direct effects of an increased flux of free fatty acids upon such processes as formation and release of triglyceride by the liver, gluconeogenesis, lipogenesis, ketone body production, glucose utilization, and insulin production.