Robins S J, Fasulo J M, Robins V F, Patton G M
Lipid Metabolism Laboratory, Boston Veterans Administration Medical Center, Massachusetts 02130.
Am J Physiol. 1989 Dec;257(6 Pt 1):E860-5. doi: 10.1152/ajpendo.1989.257.6.E860.
Studies were performed in rats to quantitate the changes in the concentration of serum triglycerides (TGs) of endogenous and exogenous origin after the acute intravenous injection of TG-rich emulsion particles. Emulsions were prepared to approximate chylomicrons and to contain a TG with a single fatty acid that could be traced during its clearance from the serum. After injection of emulsions, there was a rapid increase of not only the emulsion TG but TGs that contained a variety of other fatty acids of endogenous origin. Endogenous TGs were cleared from the serum at a slower rate than the emulsion TG and accounted for the major increase in serum TGs, especially during the latter phase of the clearance period. The increase in endogenous TGs was completely abolished by hepatectomy, which had no effect on the clearance of the emulsion TG. Results thus show that TGs of hepatic origin accumulate in the serum in response to the introduction of new TG-rich lipoproteins. Feeding rats a specific TG produced a similar result, with a pronounced rise in endogenous TGs that, like the changes after emulsion administration, was particularly evident once the TG that was fed was largely cleared from the serum. These findings are consistent with a process in which the preferential clearance of chylomicron TGs interrupts the clearance of very low density lipoprotein TGs that are produced by the liver. Consequently, the composition of serum TGs that accumulate after a meal may not reflect the composition of the meal itself.
进行了大鼠实验，以定量急性静脉注射富含甘油三酯（TGs）的乳剂颗粒后内源性和外源性血清甘油三酯浓度的变化。制备的乳剂近似乳糜微粒，并含有一种单一脂肪酸的甘油三酯，在其从血清中清除的过程中可以追踪该脂肪酸。注射乳剂后，不仅乳剂甘油三酯迅速增加，而且含有多种内源性其他脂肪酸的甘油三酯也迅速增加。内源性甘油三酯从血清中的清除速度比乳剂甘油三酯慢，并且是血清甘油三酯主要增加的原因，尤其是在清除期的后期。肝切除完全消除了内源性甘油三酯的增加，而对乳剂甘油三酯的清除没有影响。因此，结果表明，肝脏来源的甘油三酯会因引入新的富含甘油三酯的脂蛋白而在血清中积累。给大鼠喂食特定的甘油三酯也产生了类似的结果，内源性甘油三酯显著升高，与注射乳剂后的变化一样，一旦喂食的甘油三酯从血清中大量清除，这种升高就特别明显。这些发现与以下过程一致：乳糜微粒甘油三酯的优先清除中断了肝脏产生的极低密度脂蛋白甘油三酯的清除。因此，餐后积累的血清甘油三酯的组成可能无法反映餐食本身的组成。
