Mingrone G, De Gaetano A, Greco A V, Capristo E, Castagneto M, Gasbarrini G
Istituto di Clinica Medica, Università Cattolica del Sacro Cuore, Rome, Italy.
Nutrition. 1995 Sep-Oct;11(5):418-22.
Medium-chain triglycerides (MCTs) have been introduced as lipid substrates in parenteral nutrition because of their rapid and complete oxidation. Although there are many clinical studies on the use of MCTs in parenteral nutrition there are only a few studies on their kinetics; most of these studies used indirect methods (such as light scattering) to determine MCT concentrations in plasma. We determined the hydrolysis rate of MCTs to medium-chain fatty acids (MCFAs) and the disposition rate of MCFAs in nine healthy volunteers who received an intravenous bolus of MCTs as 10% MCT + 10% long-chain triglyceride solution. MCTs and MCFAs were analyzed by gas-liquid chromatography. One linear compartment model was used and its parameters were numerically estimated. The first-order transformation constant of the hydrolysis step from MCT to MCFA was 0.0964 +/- 0.0152 min-1(for 8- and 10-carbon pooled together); the rate constant for tissue MCFA uptake from plasma was 0.0725 +/- 0.0230 min-1. The apparent volumes of distribution were about 4.5 L for MCT and 19 L for MCFA in a typical 70-kg subject. The plasma half-life of MCT was 11 min and that of MCFA was 17 min. The limiting step in the clinical use of MCTs seems to be tissue uptake of MCFAs.
中链甘油三酯（MCTs）因其快速且完全氧化，已被引入作为肠外营养中的脂质底物。尽管有许多关于MCTs在肠外营养中应用的临床研究，但关于其动力学的研究却很少；这些研究大多采用间接方法（如光散射）来测定血浆中的MCT浓度。我们测定了9名健康志愿者中MCTs水解为中链脂肪酸（MCFAs）的速率以及MCFAs的处置速率，这些志愿者接受了静脉推注的10% MCT + 10%长链甘油三酯溶液。通过气液色谱法分析MCTs和MCFAs。使用了一个线性房室模型，并对其参数进行了数值估计。从MCT到MCFA的水解步骤的一级转化常数为0.0964 +/- 0.0152 min-1（8碳和10碳合并计算）；组织从血浆中摄取MCFA的速率常数为0.0725 +/- 0.0230 min-1。在一个典型的70千克受试者中，MCT的表观分布容积约为4.5升，MCFA的表观分布容积约为19升。MCT的血浆半衰期为11分钟，MCFA的血浆半衰期为17分钟。MCTs临床应用中的限速步骤似乎是MCFAs的组织摄取。
