Ultrastructural and immunohistochemical studies on endocytic pathway of high density lipoprotein (HDL) in cells.

我们应用组织化学、免疫组织化学、电镜、细胞化学和生物化学等方法研究了高密度脂蛋白（HDL）在几种细胞中的内吞途径。此外，我们还研究了低密度脂蛋白（LDL）和辣根过氧化物酶（HRP）在几种细胞中的内吞途径。用生物素标记大鼠HDL、大鼠LDL、兔HDL和兔LDL，发现HDL-生物素和LDL-生物素与肝细胞的最初相互作用发生在基底外侧（窦状隙）质膜上的结合位点。配体的内化涉及包被泡、包被囊泡、早期内体、晚期内体和溶酶体。但HDL-生物素与LDL-生物素的结合位点分布不同，高胆固醇饲料（含0.5%胆固醇）4个月对家兔肝细胞和肾上腺皮质细胞内吞HDL-生物素无抑制作用。

We used histochemistry, immunohistochemistry, electromicroscopy, cytochemistry and biochemistry to investigate the endocytic pathway of high density lipoprotein (HDL) in several cells. In addition, we examined the endocytic pathway of low density lipoprotein (LDL) and horseradish peroxidase (HRP) in several cells.HDL and LDL were isolated from normal rat and rabbit blood by sequential ultracentrifugation. Rat HDL,rat LDL,rabbit HDL and rabbit LDL were labeled with biotin.The initial interaction of HDL-biotin and LDL-biotin with hepatocytes occurred at binding sites distributed over the basolateral (sinusoidal) plasma membrane. Ligand internalization was involved coated puits, coated vesicles, early endosomes, late endosomes, and lysosomes. However, the binding sites distributed over the endocytic membrane were difference between HDL-biotin and LDL-biotin.Internalization of HDL-biotin in hepatocytes and adrenal cortical cells of rabbit was no inhibition by a hypercholesterol diet containing 0.5% cholesterol for 4 months.