title: Marked heterogeneity of human skeletal muscle lipolysis at rest.
abstract: In this study, variations in lipolysis among different muscle groups were examined by measuring local net glycerol release in vivo in healthy, normal-weight subjects (n = 11) during rested, postabsorptive conditions. Microdialysis of the gastrocnemius, deltoid, and vastus lateralis muscle regions revealed that extracellular glycerol concentrations of these three muscle regions were 84.7 +/- 6.7, 59.7 + 7.3, and 56.4 +/- 7.5 micro mol/l, respectively, and the arterial plasma glycerol concentration was 44.8 +/- 2.3 micro mol/l (P = 0.0003-0.006, gastrocnemius vs. others). Local tissue blood flow, as measured by Xe clearance, did not differ among the regions. Net glycerol release was significantly higher in gastrocnemius muscle than in the two other regions. There were no regional differences in glycerol uptake when studied during glycerol infusion. Gastrocnemius muscle showed a dominance of type 1 fibers (70%), whereas the vastus lateralis muscle had equal distribution of fiber types (P = 0.02). No differences in intramuscular triaclyceride content, perimuscular fat, or the adipocyte-specific protein perilipin were observed among the muscle regions. Triglyceride turnover in the gastrocnemius muscle was 3.3 + 1.4% over 24 h, which is about 10 times more rapid than the turnover rate in subcutaneous adipose tissue (P < 0.01). Thus there were marked differences in lipolytic activity among skeletal muscle groups at rest, possibly reflecting variations in fiber type.
authors.affiliation: Department of Medicine, Center of Metabolism and Endocrinology, Karolinska Institutet, M63 Huddinge University Hospital, SE-141 86 Stockholm, Sweden. eva.toft@ersta.se
authors.forename: Eva
authors.initials: E
authors.lastname: Hagström-Toft
authors.forename: Veronica
authors.initials: V
authors.lastname: Qvisth
authors.forename: Inger
authors.initials: I
authors.lastname: Nennesmo
authors.forename: Mikael
authors.initials: M
authors.lastname: Rydén
authors.forename: Helene
authors.initials: H
authors.lastname: Bolinder
authors.forename: Staffan
authors.initials: S
authors.lastname: Enoksson
authors.forename: Jan
authors.initials: J
authors.lastname: Bolinder
authors.forename: Peter
authors.initials: P
authors.lastname: Arner
mesh_terms: D000328:Adult; D001132:Arm; D005110:Extracellular Space / Q000378:metabolism; D005227:Fatty Acids / Q000378:metabolism; D005260:Female; D005990:Glycerol / Q000097:blood / Q000378:metabolism / Q000493:pharmacokinetics; D006801:Humans; D007866:Leg; D008066:Lipolysis / Q000502:physiology*; D008297:Male; D017551:Microdialysis; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000098:blood supply / Q000378:metabolism*; D009994:Osmolar Concentration; D010084:Oxidation-Reduction; D012039:Regional Blood Flow; D012146:Rest; D013997:Time Factors; D014280:Triglycerides / Q000378:metabolism
chemical_list: D005227:Fatty Acids; D014280:Triglycerides; D005990:Glycerol