Human Forearm Muscle Metabolism during Exercise II Uptake, release and oxidation of individual FFA and glycerol

Abstract

The uptake, release, and oxidation of individual free fatty acids (FFA) in the human forearm were studied during a 60-min. exercise period. Muscular uptake of FFA rose with the arterial concentration. The muscle showed a slight preference for linoleic and oleic acid compared to palmitic acid. The forearm RQ [respiratory quotient] indicated a constant fat oxidation during the period of exercise. The uptake of FFA covered about 50% of the fat oxidation. On the average 60% of the muscular FFA C14 uptake was oxidized to C14O2. The remaining radioactivity left the muscle as water-soluble metabolite(s). [beta]-Hydroxybutyrate leaving the muscle was labeled. No release of glycerol accompanied the release of FFA during exercise. Glycerol-1-C14 was oxidized by the exercising muscle. Glycerol dehydrogenase activity was demonstrated in human skeletal muscle.