Elimination rate of fat emulsion particles from plasma in Japanese subjects as determined by a triglyceride clamp technique

The elimination rate of emulsion triglyceride (TG) from plasma was investigated in Japanese subjects by a plasma TG clamp technique. Two different studies were performed. In Study 1, a lipid emulsion (20% long-chain triglyceride emulsion: LCT) was infused into a healthy research associate to achieve a certain concentration of TG in the plasma. Thereafter, the infusion rate was adjusted to maintain the chosen concentrations of TG in plasma (namely, 4–5 mmol/L, 3–4 mmol/L, and approximately 2 mmol/L) over a period of 160 min by measuring plasma TG concentrations at 10-min intervals. Concentrations of TG in plasma were clamped within 2.13 ± 0.13 mmol/L by an infusion rate of 0.10 g·kg−1·h−1, within 3.34 ± 0.20 mmol/L by an infusion rate of 0.14 g·kg−1·h−1, and within 4.46 ± 0.22 mmol/L by an infusion rate of 0.11 g·kg−1·h−1. The mean rate of infusion of emulsified TG that had maintained the steady concentrations of TG in plasma was limited to the very narrow range of 0.12 ± 0.02 g of TG·kg−1·h−1 regardless of the chosen concentration of TG in plasma. Concentrations of nonesterified fatty acids (NEFA) also remained at a fixed level of 1.378 ± 0.103 mEq/L regardless of the chosen concentration of TG in the plasma. Study 2 was undertaken to determine whether plasma TG concentration reached a plateau during a period when emulsion TG was infused into three different subjects at a rate of 0.12 g·kg−1·h−1. The plasma TG concentrations were steady at a level of 2.04 ± 0.32 mmol/L, and the plasma NEFA concentrations remained at a fixed level of 1.33 ± 0.13 mEq/L, over a period of 160 min after 50-min priming infusion. These results indicate that the plasma TG elimination rate was limited to the narrow range of 0.12 ± 0.02 g·kg−1·h−1 when the fat emulsion was infused into Japanese subjects in a steady state. However, the plasma TG elimination rate in Japanese subjects appeared to be lower than that of Europeans. This may be due to a difference in lipoprotein lipase activity caused by different dietary habits, namely, a lower fat intake.