Campos H, Dreon D M, Krauss R M
Department of Molecular and Nuclear Medicine, Lawrence Berkely Laboratory, University of California, Berkeley 94720, USA.
J Lipid Res. 1995 Mar;36(3):462-72.
To test whether lipoprotein lipase or hepatic lipase activities are associated with lipoprotein subclasses, and to assess the effects of dietary manipulations on these associations, enzyme activities were measured in postheparin plasma (75 U heparin/kg) from 43 healthy men who were randomly allocated to a low-fat (24% fat, 60% carbohydrate) and a high-fat (46% fat, 38% carbohydrate) diet for 6 weeks each in a cross-over design. The high-fat diet significantly increased both lipoprotein lipase (+20%, P = 0.02) and hepatic lipase (+8%, P = 0.007) activities. On both diets, hepatic lipase activity was significantly positively correlated (P < 0.01) with plasma apolipoprotein (apo)B concentrations, and with levels of small dense low density lipoprotein (LDL) III, measured by analytic ultracentrifugation as mass of lipoproteins of flotation rate (Sof) 3-5, while lipoprotein lipase activity was inversely associated with levels of LDL III (P < 0.05). Despite the cross-sectional correlations, increased hepatic lipase activity was not significantly correlated with the reduction in LDL III mass observed on the high-fat diet. Rather, changes in hepatic lipase were correlated inversely with changes in small very low density lipoproteins (VLDL) of Sof 20-40, and small intermediate density lipoproteins (VLDL) of Sof 10-16. Moreover, changes in lipoprotein lipase activity were not significantly correlated with changes in small LDL, but were positively associated with changes in small IDL of Sof 10-14, and large LDL I of Sof 7-10. Thus, while increased levels of small dense LDL are associated with a metabolic state characterized by relatively increased hepatic lipase and decreased lipoprotein lipase activity, changes in these enzymes do not appear to be primary determinants of diet-induced changes in levels of this LDL subfraction. On the other hand, increased lipoprotein lipase activity induced by high-fat feeding may contribute to the accumulation in plasma of both large LDL I and small IDL, whereas increased hepatic lipase may promote catabolism or clearance of triglyceride-rich lipoprotein remnants.
为了检测脂蛋白脂肪酶或肝脂肪酶活性是否与脂蛋白亚类相关，并评估饮食干预对这些关联的影响，对43名健康男性的肝素后血浆（75 U肝素/千克）中的酶活性进行了测量。这些男性采用交叉设计，被随机分配到低脂（24%脂肪，60%碳水化合物）和高脂（46%脂肪，38%碳水化合物）饮食组，每组各持续6周。高脂饮食显著增加了脂蛋白脂肪酶活性（+20%，P = 0.02）和肝脂肪酶活性（+8%，P = 0.007）。在两种饮食条件下，肝脂肪酶活性与血浆载脂蛋白（apo）B浓度以及通过分析超速离心法测定的小而密低密度脂蛋白（LDL）III水平（以漂浮率[Sof]为3 - 5的脂蛋白质量表示）均呈显著正相关（P < 0.01），而脂蛋白脂肪酶活性与LDL III水平呈负相关（P < 0.05）。尽管存在横断面相关性，但高脂饮食时肝脂肪酶活性增加与LDL III质量降低并无显著相关性。相反，肝脂肪酶的变化与Sof为20 - 40的小极低密度脂蛋白（VLDL）以及Sof为10 - 16的小中间密度脂蛋白（VLDL）的变化呈负相关。此外，脂蛋白脂肪酶活性的变化与小LDL的变化无显著相关性，但与Sof为10 - 14的小中间密度脂蛋白（IDL）以及Sof为7 - 10的大LDL I的变化呈正相关。因此，虽然小而密LDL水平升高与以肝脂肪酶相对增加和脂蛋白脂肪酶活性降低为特征的代谢状态相关，但这些酶的变化似乎并非饮食诱导的该LDL亚组分水平变化的主要决定因素。另一方面，高脂喂养诱导的脂蛋白脂肪酶活性增加可能有助于血浆中大型LDL I和小型IDL的蓄积，而肝脂肪酶增加可能促进富含甘油三酯的脂蛋白残粒的分解代谢或清除。
