title: Higher free fatty acid uptake in visceral than in abdominal subcutaneous fat tissue in men.
abstract: Visceral adipose tissue has been shown to have high lipolytic activity. The aim of this study was to examine whether free fatty acid (FFA) uptake into visceral adipose tissue is enhanced compared to abdominal subcutaneous tissue in vivo. Abdominal adipose tissue FFA uptake was measured using positron emission tomography (PET) and [(18)F]-labeled 6-thia-hepta-decanoic acid ([(18)F]FTHA) and fat masses using magnetic resonance imaging (MRI) in 18 healthy young adult males. We found that FFA uptake was 30% higher in visceral compared to subcutaneous adipose tissue (0.0025 +/- 0.0018 vs. 0.0020 +/- 0.0016 micromol/g/min, P = 0.005). Visceral and subcutaneous adipose tissue FFA uptakes were strongly associated with each other (P < 0.001). When tissue FFA uptake per gram of fat was multiplied by the total tissue mass, total FFA uptake was almost 1.5 times higher in abdominal subcutaneous than in visceral adipose tissue. In conclusion, we observed enhanced FFA uptake in visceral compared to abdominal subcutaneous adipose tissue and, simultaneously, these metabolic rates were strongly associated with each other. The higher total tissue FFA uptake in subcutaneous than in visceral adipose tissue indicates that although visceral fat is active in extracting FFA, its overall contribution to systemic metabolism is limited in healthy lean males. Our results indicate that subcutaneous, rather than visceral fat storage plays a more direct role in systemic FFA availability. The recognized relationship between abdominal visceral fat mass and metabolic complications may be explained by direct effects of visceral fat on the liver.
authors.affiliation: Turku PET Centre, Turku, Finland. jarna.hannukainen@tyks.fi
authors.forename: Jarna C
authors.initials: JC
authors.lastname: Hannukainen
authors.forename: Kari K
authors.initials: KK
authors.lastname: Kalliokoski
authors.forename: Ronald J M
authors.initials: RJ
authors.lastname: Borra
authors.forename: Antti P M
authors.initials: AP
authors.lastname: Viljanen
authors.forename: Tuula
authors.initials: T
authors.lastname: Janatuinen
authors.forename: Urho M
authors.initials: UM
authors.lastname: Kujala
authors.forename: Jaakko
authors.initials: J
authors.lastname: Kaprio
authors.forename: Olli J
authors.initials: OJ
authors.lastname: Heinonen
authors.forename: Tapio
authors.initials: T
authors.lastname: Viljanen
authors.forename: Merja
authors.initials: M
authors.lastname: Haaparanta
authors.forename: Patricia
authors.initials: P
authors.lastname: Iozzo
authors.forename: Riitta
authors.initials: R
authors.lastname: Parkkola
authors.forename: Pirjo
authors.initials: P
authors.lastname: Nuutila
mesh_terms: D000328:Adult; D001692:Biological Transport; D005227:Fatty Acids; D005230:Fatty Acids, Nonesterified / Q000378:metabolism*; D006801:Humans; D050152:Intra-Abdominal Fat / Q000378:metabolism*; D008279:Magnetic Resonance Imaging; D008297:Male; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D012016:Reference Values; D050507:Subcutaneous Fat, Abdominal / Q000378:metabolism*; D055815:Young Adult
chemical_list: D005227:Fatty Acids; D005230:Fatty Acids, Nonesterified; D019275:Radiopharmaceuticals; C071178:14-fluoro-6-thiaheptadecanoic acid