Vilaró S, Ramírez I, Bengtsson-Olivecrona G, Olivecrona T, Llobera M
Departament de Bioquímica i Fisiologia, Universitat de Barcelona, Spain.
Biochim Biophys Acta. 1988 Mar 25;959(2):106-17. doi: 10.1016/0005-2760(88)90021-5.
We have previously demonstrated that infusion of Intralipid to rats causes a pronounced increase of the lipoprotein lipase activity in the liver. In this paper we study where in the liver this lipoprotein lipase is located. When isolated livers from Intralipid-treated rats were perfused with heparin, substantial amounts of lipoprotein lipase were released into the perfusate. The identity of the lipase activity was demonstrated by specific inhibition with antisera to lipoprotein lipase, and to hepatic lipase, respectively, and by separation of the two lipase activities by chromatography on heparin-Sepharose. We have also studied the localization of both enzymes by an immunostaining procedure based on post-embedding incubation of ultrathin tissue sections with specific antibodies which were then visualized using protein A-colloidal gold complexes. There was no marked difference in localization for the two enzymes which were both seen at the luminal side of endothelial cells, at the interdigitations of the space of Disse and inside both hepatocytes and endothelial cells. Thus, lipoprotein lipase is present in the liver in positions similar to where the functional pool of hepatic lipase is located and analogous to where lipoprotein lipase is found in extrahepatic tissues. These results raise the possibility that the enzyme has a functional role in the liver.
我们之前已经证明，给大鼠输注脂肪乳剂会导致肝脏中脂蛋白脂肪酶活性显著增加。在本文中，我们研究了肝脏中这种脂蛋白脂肪酶的定位。当用肝素灌注来自脂肪乳剂处理大鼠的离体肝脏时，大量的脂蛋白脂肪酶释放到灌注液中。分别用抗脂蛋白脂肪酶和抗肝脂肪酶的抗血清进行特异性抑制，以及通过肝素 - 琼脂糖柱层析分离两种脂肪酶活性，证实了脂肪酶活性的一致性。我们还通过一种免疫染色程序研究了这两种酶的定位，该程序基于超薄组织切片与特异性抗体进行包埋后孵育，然后使用蛋白A - 胶体金复合物进行可视化。这两种酶的定位没有明显差异，在内皮细胞的腔面、狄氏间隙的指状交叉处以及肝细胞和内皮细胞内部均可见到。因此，脂蛋白脂肪酶在肝脏中的存在位置与肝脂肪酶的功能池所在位置相似，并且与在肝外组织中发现脂蛋白脂肪酶的位置类似。这些结果增加了该酶在肝脏中具有功能作用的可能性。
