FREE-FATTY ACID METABOLISM AND OBESITY

FFA周转测量结合脂质氧化率

FFA turnover measurements combined with lipid oxidation rate and assessment of body composition were used to investigate possible mechanisms of regulation of in vivo FFA metabolism and the inter-relationships between the metabolisms of FFA, carbohydrate, and lipoproteins. Our previous studies had shown that FFA mobilization was less per gram of fat in obese subjects. We also showed that a significant component of fatty acid turnover was non-oxidative disposal. To further examine the mechanisms of control of free-fatty acids, we have conducted studies of free-fatty acid turnover under two metabolic perturbations. One was the infusion of propranolol and the other was comparing individuals on a high-saturated fat and a low-fat, high carbohydrate diet. Propranolol infusion decreased the turnover of free-fatty acid, and this effect was greater in more obese individuals. During propranolol infusion, lipid oxidation was also increased, resulting therefore in a greatly decreased proportion of non-oxidative fatty acid disposal. During transfer to a high saturated fat diet, fatty acid production rates also declined and lipid oxidation increased, thus resulting in a significantly lower proportion of non-oxidative fatty acid disposal. The data suggest that the sympathetic nervous system plays a role in regulating the output of fatty acids from adipose stores and that obese individuals may differ in their sensitivity to this regulation. Finally, the non-oxidative component of fatty acid metabolism was lower in situations where lipid oxidation was increased. This may reflect inhibition of triglyceride re- esterification in sites other than adipose tissue.