The role of fatty acid binding protein on the metabolism of fatty acids in isolated rat hepatocytes

In isolated rat hepatocytes flavaspidic acid, a competitor with free fatty acids for the fatty-acid-binding-protein, decreased the uptake of oleic acid and triglyceride synthesis but stimulated the formation of CO₂ and ketone bodies from oleic acid. Flavaspidic acid had no effect on the utilization of octanoic acid. Stimulation of the microsomal fatty-acid-activating enzyme by the fatty-acid-binding protein was reversed by flavaspidic acid. In contrast, the binding protein inhibited the mitochondrial fatty-acid-activating enzyme. Flavaspidic acid not only prevented this inhibition but actually stimulated the enzyme activity. The results indicate that the cytosol fatty-acid-binding protein directs the metabolism of long chain fatty acids toward esterification as well as enhancing their cellular uptake.