Krauss R M, Levy R I, Fredrickson D S
J Clin Invest. 1974 Nov;54(5):1107-24. doi: 10.1172/JCI107855.
An assay has been developed for specific measurement of two different lipase activities in postheparin plasma. Lipoprotein lipase, derived from extrahepatic sources, is measured as protamine-inactivated lipase activity; hepatic lipase activity is protamine-resistant under the conditions of this assay. In 100 normal subjects, both enzyme activities were noted to be related to age and sex. Protamine-resistant lipase, which comprised 46-95% of the total activity, was highest in men over 18. Protamine-inactivated lipase activity was greatest in younger males and was age-correlated in women, doubling between the second and sixth decades. In 12 patients with hyperchylomicronemia, including five previously shown to have familial type I hyperlipoproteinemia, protamine-inactivated lipase activity was markedly reduced, whereas protamine-resistant lipase was below normal in only 1. The results were not due to lack of plasma activator, presence of plasma inhibitor, or diet, and the deficiency was not overcome by increasing the provoking dose of heparin from 10 U to 75 U/kg. Mean values for both lipase activities were not reduced in 32 other patients with hyperchylomicronemia, nine with "floating beta" lipoproteins (type III hyperlipoproteinemia), and 23 with hyperprebetalipoproteinemia (type IV). Mean protamine-resistant lipase activity was below normal in a group of four women with hypothyroidism, in whom protamine-inactivated lipase was not reduced. Both of the lipase activities were capable of hydrolyzing lipid in very low-density lipoproteins, but the relative rate of hydrolysis of chylomicrons by protamine-resistant lipase was markedly limited. These results indicate the importance of distinguishing between lipases of hepatic and extra-hepatic origin in the measurement of postheparin lipolytic activity.
已开发出一种用于特异性测量肝素后血浆中两种不同脂肪酶活性的检测方法。源自肝外来源的脂蛋白脂肪酶通过鱼精蛋白灭活的脂肪酶活性进行测量；在该检测条件下，肝脂肪酶活性对鱼精蛋白具有抗性。在100名正常受试者中，两种酶活性均与年龄和性别有关。占总活性46%至95%的鱼精蛋白抗性脂肪酶在18岁以上男性中最高。鱼精蛋白灭活的脂肪酶活性在年轻男性中最高，在女性中与年龄相关，在第二个十年到第六个十年之间增加了一倍。在12例高乳糜微粒血症患者中，包括5例先前显示为家族性I型高脂蛋白血症的患者，鱼精蛋白灭活的脂肪酶活性明显降低，而鱼精蛋白抗性脂肪酶仅1例低于正常水平。结果不是由于血浆激活剂缺乏、血浆抑制剂存在或饮食所致，增加肝素激发剂量从10 U/kg至75 U/kg也不能克服这种缺陷。在另外32例高乳糜微粒血症患者、9例“漂浮β”脂蛋白（III型高脂蛋白血症）患者和23例高前β脂蛋白血症（IV型）患者中，两种脂肪酶活性的平均值均未降低。一组4例甲状腺功能减退的女性中，平均鱼精蛋白抗性脂肪酶活性低于正常水平，而鱼精蛋白灭活的脂肪酶未降低。两种脂肪酶活性均能够水解极低密度脂蛋白中的脂质，但鱼精蛋白抗性脂肪酶对乳糜微粒的相对水解速率明显受限。这些结果表明在测量肝素后脂解活性时区分肝源性和肝外源性脂肪酶的重要性。
