Marked Re-Utilization of Free Fatty Acids During Activated Lipolysis in Human Skeletal Muscle.

Staffan Enoksson, Eva Hagström-Toft, Joakim Nordahl, Kjell Hultenby, Nils Pettersson, Bengt Isaksson, Johan Permert, Rolf Wibom, Cecilia Holm, Jan Bolinder, Peter Arner

Research output: Contribution to journalArticlepeer-review

14 Citations (SciVal)

Abstract

Release of glycerol and free fatty acids (FFA) was investigated in human skeletal muscle strips. In the basal state, glycerol and FFA were released at almost equimolar rates (0.3 nmol/ng tissue.90 min). A nonselective beta-adrenoceptor agonist, isoprenaline, caused a concentration-dependent stimulation of glycerol release, whereas FFA release was unaffected. Basal and isoprenaline-induced glycerol release correlated positively with the age of the donors (r = 0.5, P < 0.005) but not with their body mass index (P > or = 0.4). Biochemical experiments with hormone-sensitive lipase (HSL) showed that most enzyme activity was both in the cytosol and mitochondrial fraction and that it constituted the common long and active form of the protein. Electron microscopy studies in rat skeletal muscle using labeled highly specific HSL antibodies verified the cytosolic location of HSL and, furthermore, indicated an accumulation of HSL-adjoining mitochondria. These results suggest that FFA produced in myocytes during catecholamine-induced lipolysis are retained by the muscle and, therefore by inference, reused. It is conceivable that efficient hydrolysis of acylglycerol by HSL located in the cytosol as well as near the mitochondria may facilitate mitochondrial FFA oxidation. In addition, muscle lipolysis activity increases during aging and may be independent of total body fat.
Original languageEnglish
Pages (from-to)1189-1195
JournalJournal of Clinical Endocrinology and Metabolism
Volume90
Issue number2
DOIs
Publication statusPublished - 2005

Subject classification (UKÄ)

  • Endocrinology and Diabetes
  • Basic Medicine

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