Adipocyte Proteins and Storage of Endogenous Fatty Acids in Visceral and Subcutaneous Adipose Tissue in Severe Obesity

Objective: This study tested whether substrate concentrations or fatty acid storage proteins predict storage of endogenous lipids in visceral adipose tissue (VAT) and upper body subcutaneous adipose tissue (UBSQ) fat. Methods: The day prior to surgery, 25 patients undergoing bariatric procedures received an infusion of autologous [1-¹⁴C]triolein-labeled very low-density lipoprotein (VLDL) particles, and during surgery, they received a continuous [U-¹³C]palmitate infusion/bolus [9,10-³H]palmitate tracer. VAT and UBSQ fat were collected to measure VLDL-triglyceride (TG) storage, direct free fatty acid (FFA) storage rates, CD36 content, lipoprotein lipase (LPL), acyl-CoA synthetase, diacylglycerol acetyl-transferase, and glycerol-3-phosphate acyltransferase activities. Results: Storage of VLDL-TG and FFA-palmitate in UBSQ and VAT was not different. Plasma palmitate concentrations correlated with palmitate storage rates in UBSQ and VAT (r = 0.46, P = 0.02 and r = 0.46, P = 0.02, respectively). In VAT, VLDL-TG storage was correlated with VLDL concentrations (r = 0.53, P < 0.009) and LPL (r = 0.42, P < 0.05). In UBSQ, VLDL-TG storage was correlated with LPL (r = 0.42, P < 0.05). CD36, acyl-CoA synthetase, glycerol-3-phosphate acyltransferase, and diacylglycerol acetyl-transferase were not correlated with VLDL-TG or palmitate storage. Conclusions: Adipose storage of VLDL-TG is predicted by VLDL-TG concentrations and LPL; FFA concentrations predict direct adipose tissue FFA storage rates.