title: Storage of circulating free fatty acid in adipose tissue of postabsorptive humans: quantitative measures and implications for body fat distribution.
abstract: OBJECTIVE
  Preferential upper-body fat gain, a typical male pattern, is associated with a greater cardiometabolic risk. Regional differences in lipolysis and meal fat storage cannot explain sex differences in body fat distribution. We examined the potential role of the novel free fatty acid (FFA) storage pathway in determining body fat distribution in postabsorptive humans and whether adipocyte lipogenic proteins (CD36, acyl-CoA synthetases, and diacylglycerol acyltransferase) predict differences in FFA storage.
  
  
  METHODS
  Rates of postabsorptive FFA (palmitate) storage into upper-body subcutaneous (UBSQ) and lower-body subcutaneous (LBSQ) fat were measured in 28 men and 53 premenopausal women. Stable and radiolabeled palmitate tracers were intravenously infused followed by subcutaneous fat biopsies. Body composition was assessed with a combination of dual-energy X-ray absorptiometry and computed tomography.
  
  
  RESULTS
  Women had greater FFA (palmitate) storage than men in both UBSQ (0.37 ± 0.15 vs. 0.27 ± 0.18 μmol · kg(-1) · min(-1), P = 0.0001) and LBSQ (0.42 ± 0.19 vs. 0.22 ± 0.11 μmol · kg(-1) · min(-1), P < 0.0001) fat. Palmitate storage rates were significantly greater in LBSQ than UBSQ fat in women, whereas the opposite was true in men. Plasma palmitate concentration positively predicted palmitate storage in both depots and sexes. Adipocyte CD36 content predicted UBSQ palmitate storage and sex-predicted storage in LBSQ fat. Palmitate storage rates per kilogram fat did not decrease as a function of fat mass, whereas lipolysis did.
  
  
  CONCLUSIONS
  The FFA storage pathway, which had remained undetected in postabsorptive humans until recently, can have considerable, long-term, and sex-specific effects on body fat distribution. It can also offer a way of protecting the body from excessive circulating FFA in obesity.
authors.affiliation: Endocrine Research Unit, Mayo Clinic, Rochester, Minnesota, USA.
authors.forename: Christina
authors.initials: C
authors.lastname: Koutsari
authors.forename: Asem H
authors.initials: AH
authors.lastname: Ali
authors.forename: Manpreet S
authors.initials: MS
authors.lastname: Mundi
authors.forename: Michael D
authors.initials: MD
authors.lastname: Jensen
mesh_terms: D000328:Adult; D050218:Body Fat Distribution; D018955:CD36 Antigens / Q000378:metabolism; D003066:Coenzyme A Ligases / Q000378:metabolism; D051048:Diacylglycerol O-Acyltransferase / Q000378:metabolism; D005230:Fatty Acids, Nonesterified / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D010168:Palmitates / Q000378:metabolism; D012727:Sex Characteristics; D050151:Subcutaneous Fat / Q000378:metabolism*; D050507:Subcutaneous Fat, Abdominal / Q000378:metabolism; D013848:Thigh
chemical_list: D018955:CD36 Antigens; D005230:Fatty Acids, Nonesterified; D010168:Palmitates; D051048:Diacylglycerol O-Acyltransferase; D003066:Coenzyme A Ligases