Clark S B, Norum K R
J Lipid Res. 1977 May;18(3):293-300.
The lecithin-cholesterol acyl transferase (LCAT) activity in rat mesenteric lymph was examined as a possible source of chylomicron cholesteryl ester. Lymph activity was only 2-3% of rat serum activity. Removal of d less than 1.006 lipoproteins increased lymph LCAT activity, but only to 6-8% of that of serum. Relative to total cholesterol in the d greater than 1.08 g/ml fractions, lymph LCAT activity in lymph from fasting rats was less than serum, but in lymph from nonfasting rats the ratio LCAT/HDL-cholesterol reached levels greater than serum, suggesting a contribution of enzyme from the gut. Both LCAT activity and HDL concentration in mesenteric lymph increased during feeding. Subfractions of lymph that inhibited serum LCAT were: chylomicrons, VLDL, chylomicron lipid, VLDL apoprotein, and HDL apoprotein. In the rat, the low LCAT activity of mesenteric lymph was in part due to the low enzyme concentration present, and the activity was apparently lowered further by lipid-rich lipoproteins that inhibited the reaction. Enzyme inhibition due to the apoprotein fractions of lipoproteins is probably minor in the rat in vivo.
对大鼠肠系膜淋巴中的卵磷脂胆固醇酰基转移酶（LCAT）活性进行了检测，以确定其是否可能是乳糜微粒胆固醇酯的来源。淋巴中的活性仅为大鼠血清活性的2 - 3%。去除密度小于1.006的脂蛋白可增加淋巴LCAT活性，但仅达到血清活性的6 - 8%。相对于密度大于1.08 g/ml组分中的总胆固醇，禁食大鼠淋巴中的LCAT活性低于血清，但非禁食大鼠淋巴中的LCAT/高密度脂蛋白胆固醇比值达到高于血清的水平，提示肠道有酶的贡献。喂养期间，肠系膜淋巴中的LCAT活性和高密度脂蛋白浓度均升高。抑制血清LCAT的淋巴亚组分包括：乳糜微粒、极低密度脂蛋白、乳糜微粒脂质、极低密度脂蛋白载脂蛋白和高密度脂蛋白载脂蛋白。在大鼠中，肠系膜淋巴中LCAT活性低部分是由于存在的酶浓度低，且富含脂质的脂蛋白抑制反应，使活性进一步明显降低。脂蛋白载脂蛋白组分引起的酶抑制在大鼠体内可能作用较小。
