Daggy B P, Bensadoun A
Biochim Biophys Acta. 1986 Jun 27;877(2):252-61. doi: 10.1016/0005-2760(86)90302-4.
In order to explore the in vivo function of hepatic lipase, rats were injected with goat anti-rat hepatic lipase serum which produced a complete and specific inhibition of heparin-releasable hepatic lipase. In the fasting rats, protein, phospholipid and free cholesterol expressed as either mass or percent weight increased significantly in low-density lipoprotein (LDL) and high-density lipoprotein 2 (HDL-2) fractions. These three constituents were not affected in the VLDL and HDL-3 lipoproteins. In the fat-loaded (1 ml corn oil) rat, 6 h post inhibition of hepatic lipase triacylglycerol, phospholipid and free cholesterol concentrations in the d less than 1.006 fraction were 2.5-fold higher in the inhibited animals than in the control rats. The composition of the d less than 1.006 fraction was also affected. Expressed as percent mass, protein was lower (5.2 +/- 1.2 vs. 10.3 +/- 1.5, P less than 0.001) as was cholesteryl ester (1.7 +/- 0.7 vs. 2.6 +/- 0.4, P less than 0.01); triacylglycerol was elevated (77.2 +/- 4.0 vs. 72.6 +/- 2.4, P less than 0.025), as was free cholesterol (3.0 +/- 0.6 vs. 2.4 +/- 0.2, P less than 0.025). Overall, inhibition lowered the ratio of surface-to-core constituents suggesting a larger mean particle diameter. SDS-polyacrylamide gel electrophoresis showed the intermediate- and low-density lipoprotein from treated rats to be significantly enriched in apolipoprotein B-48. In the LDL fraction, apolipoprotein B-48 accounted for 62 +/- 14% of the total apolipoprotein B in the inhibited rats, vs. 12 +/- 2% in the control rats. The above results support the previously described in vivo function of hepatic lipase as a phospholipase. In addition, the results demonstrate a role of hepatic lipase in the catabolism of chylomicrons. Since removal of apolipoprotein B-48-containing lipoproteins is dependent upon apolipoprotein E, their appearance in the LDL fraction implies a masking of apolipoprotein E-binding determinants.
为了探究肝脂酶的体内功能，给大鼠注射山羊抗大鼠肝脂酶血清，该血清可完全且特异性地抑制肝素可释放的肝脂酶。在禁食大鼠中，以质量或重量百分比表示的蛋白质、磷脂和游离胆固醇在低密度脂蛋白（LDL）和高密度脂蛋白2（HDL - 2）组分中显著增加。这三种成分在极低密度脂蛋白（VLDL）和HDL - 3脂蛋白中未受影响。在喂食脂肪（1毫升玉米油）的大鼠中，抑制肝脂酶6小时后，密度小于1.006组分中的三酰甘油、磷脂和游离胆固醇浓度在受抑制动物中比对照大鼠高2.5倍。密度小于1.006组分的组成也受到影响。以质量百分比表示，蛋白质含量较低（5.2±1.2对10.3±1.5，P＜0.001），胆固醇酯含量也较低（1.7±0.7对2.6±0.4，P＜0.01）；三酰甘油升高（77.2±4.0对72.6±2.4，P＜0.025），游离胆固醇也升高（3.0±0.6对2.4±0.2，P＜0.025）。总体而言，抑制作用降低了表面成分与核心成分的比例，表明平均颗粒直径更大。十二烷基硫酸钠 - 聚丙烯酰胺凝胶电泳显示，处理过的大鼠的中密度和低密度脂蛋白中载脂蛋白B - 48显著富集。在LDL组分中，载脂蛋白B - 48在受抑制大鼠中占总载脂蛋白B的62±14%，而在对照大鼠中为12±2%。上述结果支持了先前描述的肝脂酶作为磷脂酶的体内功能。此外，结果证明了肝脂酶在乳糜微粒分解代谢中的作用。由于含载脂蛋白B - 48的脂蛋白的清除依赖于载脂蛋白E，它们在LDL组分中的出现意味着载脂蛋白E结合决定簇被掩盖。
