Blomhoff R, Helgerud P, Rasmussen M, Berg T, Norum K R
Proc Natl Acad Sci U S A. 1982 Dec;79(23):7326-30. doi: 10.1073/pnas.79.23.7326.
We have studied hepatic uptake of chylomicron retinyl ester. Chylomicrons were obtained from intestinal lymph of rats that were given retinol in groundnut oil by intraduodenal injection. When lymph was injected intravenously into normal rats, the radioactivity was cleared from blood with t1/2 approximately equal to 10 min. Retinyl ester was taken up initially by the liver, which, after 30 min, contained 80-90% of the radioactivity injected. Initially, most of the radioactivity was in hepatocytes, but after 30 min it disappeared from these cells and reappeared in nonparenchymal liver cells. After 2 hr these cells contained more radioactivity than the hepatocytes. When lymph was injected into vitamin A-deficient rats or rats given vitamin A in the form of retinoic acid, the plasma clearance and initial hepatic uptake of radioactivity were similar to that found in control animals. However, the nonparenchymal cells in these animals did not accumulate radioactivity. The current data suggest that vitamin A (in chylomicron remnants) is taken up initially by hepatocytes and then is released from these cells and delivered mainly to nonparenchymal liver cells in normal animals. In vitamin A-deficient rats, the vitamin is transferred from the hepatocytes to extrahepatic tissues.
我们研究了乳糜微粒视黄醇酯的肝脏摄取情况。乳糜微粒取自经十二指肠注射花生油中视黄醇的大鼠的肠淋巴液。当将淋巴液静脉注射到正常大鼠体内时，放射性物质从血液中清除的半衰期约为10分钟。视黄醇酯最初被肝脏摄取，30分钟后，肝脏中含有注射放射性物质的80 - 90%。最初，大部分放射性物质存在于肝细胞中，但30分钟后它从这些细胞中消失，并重新出现在非实质肝细胞中。2小时后，这些细胞中的放射性物质比肝细胞中的更多。当将淋巴液注射到维生素A缺乏的大鼠或给予视黄酸形式维生素A的大鼠体内时，血浆清除率和放射性物质的初始肝脏摄取与对照动物相似。然而，这些动物的非实质细胞没有积累放射性物质。目前的数据表明，维生素A（存在于乳糜微粒残粒中）最初被肝细胞摄取，然后从这些细胞中释放出来，并主要输送到正常动物的非实质肝细胞中。在维生素A缺乏的大鼠中，维生素从肝细胞转移到肝外组织。
