Effects of caloric intake on clearance of injected lipids in rabbits and rats

¹ U.S. Army Medical Research and Nutrition Laboratory, Fitzsimons General Hospital, Denver, Colorado

Rabbits fasted 3 and 10 days displayed marked increases in serum total fatty acids and total cholesterol, limited increases in lipid phosphorus and a distinct inability to clear intravenously injected triglycerides from the serum. Limited feeding in which rabbits were losing weight over a 10-day period resulted in essentially no change, either in serum lipid components or lipid removal rates. The adverse effects of fasting on serum lipid clearance appeared to be partially overcome by injecting additional glucose at the time of lipid administration, and completely overcome by giving heparin intravenously 15 minutes prior to lipid injection. Rats fasted 4 days showed decreased levels of serum total fatty acids, lipid phosphorus and total cholesterol, but maintained normal rates of serum lipid clearance. Limited-fed rats showed less pronounced decreases in serum total fatty acids, lipid phosphorus and total cholesterol, and also maintained normal serum lipid clearance.