Diraison F, Beylot M
Laboratoire de Physiopathologie Métabolique et Rénale, Lyon, France.
Am J Physiol. 1998 Feb;274(2):E321-7. doi: 10.1152/ajpendo.1998.274.2.E321.
To measure 1) the contribution of hepatic de novo lipogenesis (DNL) and plasma free fatty acid (FFA) reesterification to plasma triglyceride (TG) secretion and 2) the role of oxidation and hepatic and extrahepatic reesterification in FFA utilization, five normal subjects drank deuterate water and were infused (postabsorptive state) with [1-13C]palmitate and [1,2,3-2H5]glycerol. Total lipid oxidation (Lox) was measured by indirect calorimetry. FFA oxidation (2.76 +/- 0.65 mumol.kg.-1.min-1) accounted for 45% of FFA turnover rate (Rt) (1.04 mumol.kg-1.min-1) and 91% of Lox; FFA reesterification was 3.27 +/- 0.54 mumol.kg-1.min-1. Fractional and absolute TG Rt were 0.21 +/- 0.02 h-1 and 0.11 +/- 0.05 mumol.kg-1.min-1. DNL accounted for 3.9 +/- 0.9% of TG secretion, and hepatic FFA reesterification accounted for 49.4 +/- 5.7%; this last process represented a utilization of FFA of 0.16 +/- 0.02 mumol.kg-1.min-1. We conclude that, in the postabsorptive state, 1) DNL and FFA reesterification account for only 50-55% of TG secretion, the remaining presumably being provided by stored lipids or lipoproteins taken up by liver, 2) most reesterification occurs in extrahepatic tissues, and 3) oxidation and reesterification each contribute about one-half to FFA utilization; FFA oxidation accounts for almost all Lox.
为测定1）肝脏从头脂肪生成（DNL）和血浆游离脂肪酸（FFA）再酯化对血浆甘油三酯（TG）分泌的贡献，以及2）氧化和肝脏及肝外再酯化在FFA利用中的作用，五名正常受试者饮用了重水，并在（吸收后状态）输注了[1-¹³C]棕榈酸酯和[1,2,3-²H₅]甘油。通过间接量热法测量总脂质氧化（Lox）。FFA氧化（2.76±0.65μmol·kg⁻¹·min⁻¹）占FFA周转率（Rt）（1.04μmol·kg⁻¹·min⁻¹）的45%，占Lox的91%；FFA再酯化率为3.27±0.54μmol·kg⁻¹·min⁻¹。TG的分数周转率和绝对周转率分别为0.21±0.02 h⁻¹和0.11±0.05μmol·kg⁻¹·min⁻¹。DNL占TG分泌的3.9±0.9%，肝脏FFA再酯化占49.4±5.7%；最后这个过程代表FFA的利用率为0.16±0.02μmol·kg⁻¹·min⁻¹。我们得出结论，在吸收后状态下，1）DNL和FFA再酯化仅占TG分泌的50 - 55%，其余可能由肝脏摄取的储存脂质或脂蛋白提供，2）大多数再酯化发生在肝外组织，3）氧化和再酯化对FFA利用的贡献各约占一半；FFA氧化几乎占所有的Lox。
