title: Lipid metabolism in omental adipose tissue during operative surgery.
abstract: BACKGROUND
  Omental adipose tissue is a pure depot of visceral adipose tissue. We investigated the regulation of lipid metabolism in human omental tissue in vivo by the arterio-venous technique.
  
  
  METHODS
  Six adults were studied while undergoing elective colonic surgery. Their omental vein was cannulated intraoperatively, and after obtaining the baseline blood samples, 50 ml of 50% dextrose solution was given intravenously and simultaneous arterio-venous samples were taken for the next 2 h. Concentration differences of lipid metabolites, glucose, and lactate were measured across the arterio-venous bed. The rates of action of hormone-sensitive lipase (HSL) and lipoprotein lipase (LPL) were calculated by stoichiometric analysis and the rate of re-esterification of nonesterified fatty acids (NEFA) was determined.
  
  
  RESULTS
  After an overnight fast there was a significant release of NEFA and glycerol from the omental adipose tissue (P <0.05, P <0.05). Intravenous glucose load caused a significant reduction in the arterial NEFA and glycerol concentrations (P <0.05, P <0.05), but only the arterio-venous concentration of NEFA decreased significantly (P <0.05). There was no significant change in the arterio-venous concentration difference of glycerol, and the relative rate of action of HSL decreased, but not significantly (P=0.09 at 30 min; P=0.054 at 120 min). The ratio of release of NEFA to glycerol changed significantly (ANOVA; P <0.05) from 2.93:1 to 0.1:1.
  
  
  CONCLUSIONS
  The net release of NEFA by omental adipose tissue is primarily regulated by their local re-esterification. The change in the rate of action of HSL and LPL plays a minor role in the net release of NEFA by omental adipose tissue.
authors.affiliation: Department of Upper Gastrointestinal Surgery, Department of Surgery, Sydney University, Royal North Shore Hospital, St Leonnards, Australia. jaswinder.samra@optusnet.com.au
authors.forename: Jaswinder Singh
authors.initials: JS
authors.lastname: Samra
authors.forename: Paul
authors.initials: P
authors.lastname: Sved
authors.forename: David
authors.initials: D
authors.lastname: Sullivan
authors.forename: Thomas Jonathan
authors.initials: TJ
authors.lastname: Hugh
authors.forename: Ross Cyril
authors.initials: RC
authors.lastname: Smith
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism*; D000368:Aged; D001786:Blood Glucose; D003082:Colectomy; D005230:Fatty Acids, Nonesterified / Q000378:metabolism; D005260:Female; D005990:Glycerol / Q000378:metabolism; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D050356:Lipid Metabolism; D008071:Lipoprotein Lipase / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009852:Omentum / Q000378:metabolism*; D012004:Rectal Neoplasms / Q000601:surgery; D002787:Sterol Esterase / Q000378:metabolism; D016896:Treatment Outcome; D014280:Triglycerides / Q000378:metabolism
chemical_list: D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D014280:Triglycerides; D019344:Lactic Acid; D002787:Sterol Esterase; D008071:Lipoprotein Lipase; D005990:Glycerol