The optimal infusion rate of medium-chain triglyceride/long-chain triglyceride emulsion (MCT/LCT) during plasma insulin clamp

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As medium-chain triglyceride emulsions (MCT) are more rapidly hydrolyzed than long-chain triglyceride emulsions (LCT), MCT/LCT tends to be infused faster than LCT.The purpose of this research project was to determine the most appropriate infusion rate for MCT/LCT to stabilize plasma concentrations of triglyceride (TG), being equivalent to the optimal infusion rate of the emulsion. A TG clamp was set up by raising the mean (]SY.+-。[) s.d.concentrations of TG in plasma, being 1.08 (]SY.+-。[) 0.18 delta-mmol/l for LCT,and 1.65 (]SY.+-。[) 0.31 delta-mmol/l for MCT/LCT after a 50-min priming infusion of each emulsion. Thereafter, the infusion rate of lipid was controlled every 10 min to maintain a steady concentration of TG for a period of 150 min. A constant infusion of glucose at 0.32 g/kg/h was given for the test period. The weight-based rate of the infusion to maintain a steady state of plasma TG concentrations did not differ between MCT/LCT and LCT,being 0.125 (]SY.+-。[) 0.013 versus 0.117 (]SY.+-。[) 0.021 g/kg/h, while the molar-based infusion rate was 0.203 (]SY.+-。[) 0.021 mmol/kg/h for MCT/LCT and 0.132 (]SY.+-。[) 0.023 mmol/kg/h for LCT.These results suggest that although 54% more molar MCT/LCT can be hydrolyzed during a constant infusion, MCT/LCT should not be infused at a rate faster than 0.1 g/kg/h under a steady state.Apolipoprotein C-II (apo C-II) is essential for TG hydrolysis. It was investigated in vitro if the amounts of apo C-II acquired by lipid particles are different between MCT and LCT.The results demonstrated that there was no differences in the amounts of in vitro transfer of apo C-II from high-density lipoprotein to lipid particles between MCT and LCT.However, it was suggrested that MCT-TGs require less amounts of apo C-II than LCT in the process of hydrolysis, since the mean amount of apo C-II acquired by one micro-mol of MCT-TG was less than that acquired by one micro-mol of LCT-TG.