Plasma free fatty acid storage in subcutaneous and visceral adipose tissue in postabsorptive women.
OBJECTIVE
We assessed the direct (VLDL-triglycerides [VLDL-TG] independent) storage of circulating free fatty acids (FFAs) in visceral and subcutaneous fat in postabsorptive women.


METHODS
Twelve women (BMI 29.6 +/- 6.6 kg/m(2)) received an identical, intravenous bolus dose of [1-(14)C]oleate followed by timed subcutaneous fat biopsies (abdominal and femoral) and then omental fat biopsy during tubal ligation surgery. Regional fat masses were assessed by combining dual-energy X-ray absorptiometry and computed tomography scanning. Separately, we assessed the fraction of FFA tracer entering VLDL-TG over the time representing the delay in collecting omental fat.


RESULTS
Site-specific fat specific activity (SA) (dpm/g lipid) decreased as a function of fat mass in both upper-body subcutaneous (UBSQ) and visceral fat depots. These patterns are consistent with dilution of a relatively fixed amount of FFA tracer within progressively greater amounts of fat. Interestingly, femoral SA did not vary as a function of lower-body subcutaneous (LBSQ) fat mass. [1-(14)C]oleate storage per million LBSQ adipocytes was positively associated with LBSQ fat mass, but no significant relationships were observed in UBSQ or visceral fat depot. The fraction of [1-(14)C]oleate stored in UBSQ, LBSQ, and visceral fat was 6.7 +/- 3.2, 4.9 +/- 3.4, and 1.0 +/- 0.3%, respectively. Only approximately 4% of the tracer traversed VLDL-TG over 9.5 h.


CONCLUSIONS
The increase in FFA tracer storage per adipocyte as a function of LBSQ fat mass implies that LBSQ adipocytes, in contrast to UBSQ and omental adipocytes, store more FFA in women with greater adiposity. The direct FFA storage pathway might play a role in favoring lower-body fat accumulation in women.
Koutsari
Christina
C
Endocrine Research Unit, 5-194 Joseph, Mayo Clinic, Rochester, MN 55905, USA.
Dumesic
Daniel A
DA
Patterson
Bruce W
BW
Votruba
Susanne B
SB
Jensen
Michael D
MD
D017667:Adipocytes / Q000378:metabolism; D000273:Adipose Tissue / Q000033:anatomy & histology / Q000378:metabolism*; D001706:Biopsy; D001823:Body Composition; D015992:Body Mass Index; D004041:Dietary Fats; D005230:Fatty Acids, Nonesterified / Q000097:blood*; D005260:Female; D006801:Humans; D007275:Injections, Intravenous; D007408:Intestinal Absorption; D019301:Oleic Acid / Q000008:administration & dosage / Q000378:metabolism; D019308:Palmitic Acid / Q000097:blood; D012867:Skin; D014280:Triglycerides / Q000097:blood; D014304:Triolein / Q000008:administration & dosage / Q000378:metabolism; D014781:Viscera
D004041:Dietary Fats; D005230:Fatty Acids, Nonesterified; D014280:Triglycerides; D014304:Triolein; D019301:Oleic Acid; D019308:Palmitic Acid