This Article Full Text Full Text (PDF) All Versions of this Article: 90/2/1189    most recent Author Manuscript (PDF) Submit a related Letter to the Editor Purchase Article View Shopping Cart Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Enoksson, S. Articles by Arner, P. Search for Related Content PubMed PubMed Citation Articles by Enoksson, S. Articles by Arner, P. Related Collections Lipid

Marked Reutilization of Free Fatty Acids during Activated Lipolysis in Human Skeletal Muscle

Departments of Surgery (S.E., N.P., B.I., J.P.), Medicine (E.H.-T., J.B., P.A.), and Orthopedics (J.N.), Clinical Research Center at Karolinska Institutet (K.H.), and Department of Medical Laboratory Sciences and Technology (R.W.), the Karolinska University Hospital Huddinge, S-141 86 Stockholm, Sweden; and Department of Cell and Molecular Biology (C.H.), Lund University, 22100 Lund, Sweden

Address all correspondence and requests for reprints to: Staffan Enoksson, M.D., Ph.D., Department of Vascular Surgery, Center for Surgical Sciences, M81, Karolinska University Hospital Huddinge, S-141 86 Stockholm, Sweden. E-mail: staffan.enoksson{at}cfss.ki.se.

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 ß-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 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.

This article has been cited by other articles:

				M. G. Cree and R. R. Wolfe Postburn trauma insulin resistance and fat metabolism Am J Physiol Endocrinol Metab, January 1, 2008; 294(1): E1 - E9. [Abstract] [Full Text] [PDF]

				M. A. Tarnopolsky, C. D. Rennie, H. A. Robertshaw, S. N. Fedak-Tarnopolsky, M. C. Devries, and M. J. Hamadeh Influence of endurance exercise training and sex on intramyocellular lipid and mitochondrial ultrastructure, substrate use, and mitochondrial enzyme activity Am J Physiol Regulatory Integrative Comp Physiol, March 1, 2007; 292(3): R1271 - R1278. [Abstract] [Full Text] [PDF]