title: Effects of increased free fatty acid availability on adipose tissue fatty acid storage in men.
abstract: BACKGROUND
  A portion of free fatty acids (FFA) released from adipose tissue lipolysis are re-stored in adipocytes via direct uptake. Rates of direct adipose tissue FFA storage are much greater in women than men, but women also have greater systemic FFA flux and more body fat.
  
  
  OBJECTIVE
  We tested the hypotheses that experimental increases in FFA in men would equalize the rates of direct adipose tissue FFA storage in men and women.
  
  
  METHODS
  We used a lipid emulsion infusion to raise FFA in men to levels seen in post-absorptive women. Direct FFA storage (μmol · kg fat(-1) · min(-1)) rates in abdominal and femoral fat was assessed using stable isotope tracer infusions to measure FFA disappearance rates and an iv FFA radiotracer bolus/timed biopsy.
  
  
  METHODS
  These studies were performed in a Clinical Research Center.
  
  
  METHODS
  Data from 13 non-obese women was compared with that from eight obese and eight non-obese men.
  
  
  METHODS
  The men received a lipid emulsion infusion to raise FFA.
  
  
  METHODS
  We measured the rates of direct FFA storage in abdominal and femoral adipose tissue.
  
  
  RESULTS
  The three groups were similar in age and FFA flux by design; obese men had similar body fat percentage as non-obese women. Despite matching for FFA concentrations and flux, FFA storage per kg abdominal (P < .01) and femoral (P < .001) fat was less in both lean and obese men than in non-obese women. Abdominal FFA storage rates were correlated with proteins/enzymes in the FFA uptake/triglyceride synthesis pathway in men.
  
  
  CONCLUSIONS
  The lesser rates of direct FFA adipose tissue in men compared with women cannot be explained by reduced FFA availability.
authors.affiliation: Endocrine Research Unit, Mayo Clinic, Rochester, Minnesota 55905.
authors.forename: Manpreet S
authors.initials: MS
authors.lastname: Mundi
authors.forename: Chistina
authors.initials: C
authors.lastname: Koutsari
authors.forename: Michael D
authors.initials: MD
authors.lastname: Jensen
mesh_terms: D000106:Acetate-CoA Ligase / Q000378:metabolism; D017667:Adipocytes / Q000648:ultrastructure; D000273:Adipose Tissue / Q000378:metabolism*; D000328:Adult; D001706:Biopsy; D001823:Body Composition / Q000502:physiology; D018955:CD36 Antigens / Q000378:metabolism; D048429:Cell Size; D051048:Diacylglycerol O-Acyltransferase / Q000378:metabolism; D005227:Fatty Acids / Q000378:metabolism*; D005230:Fatty Acids, Nonesterified / Q000097:blood*; D005260:Female; D006801:Humans; D008297:Male; D009765:Obesity / Q000097:blood; D012727:Sex Characteristics
chemical_list: D018955:CD36 Antigens; D005227:Fatty Acids; D005230:Fatty Acids, Nonesterified; D051048:Diacylglycerol O-Acyltransferase; D000106:Acetate-CoA Ligase