Disappearance of two major phosphatidylcholines from plasma is predominantly via LCAT and hepatic lipase
Disappearance of two major phosphatidylcholines from plasma is predominantly via LCAT and hepatic lipase
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DOI：
10.1152/ajpendo.1996.271.6.e1073
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发表时间：
1996-12-01
影响因子：
5.1
通讯作者：
Schwartz, CC
中科院分区：
文献类型：
--
作者：
Shamburek, RD;Zech, LA;Schwartz, CC
比较了大鼠血浆中主要磷脂酰胆碱（PC）物质1-硬脂酰-2-花生四烯酸-磷脂酰胆碱（SAPC）的代谢与1-棕榈酰-2-亚油酰-PC（PLPC）的代谢。分别给予含有用H-3和C-14同位素在sn-2脂肪酸中标记的SAPC和PLPC示踪剂的高密度脂蛋白。耗尽大鼠的内源性胆汁酸，并通过回肠输注疏水性范围广泛的单个胆汁酸。血浆中SAPC和PLPC的半衰期分别为48和57 min。在1 h时从血浆中消失的大多数H-3活性在肝脏中以1-棕榈酰-2-花生四烯酰-PC、SAPC和1-油酰-2-花生四烯酰-PC的形式存在，表明磷脂酶A（1）水解血浆SAPC形成2-花生四烯酰-溶血磷脂酰胆碱，后者在肝脏中被再酰化。如前所述，血浆PLPC也经历磷脂酶A（1）水解。在血浆胆固醇花生四烯酸酯中累积的H-3剂量分数比胆固醇亚油酸酯中C-14剂量分数高2 - 3倍。开发了SAPC和PLPC的多房室模型，其中包括溶血磷脂酰胆碱和胆固醇酯。胆汁酸不影响血浆PC代谢。卵磷脂-胆固醇酰基转移酶和磷脂酶A（1）（肝脂肪酶）水解占血浆中消失的SAPC和PLPC的90%以上; SAPC和PLPC作为肝脂肪酶的底物相当，但卵磷脂-胆固醇酰基转移酶首选SAPC。
Metabolism of 1-stearoyl-2-arachidonyl-phosphatidylcholine (SAPC), a major phosphatidylcholine (PC) species in rat plasma, was compared with 1-palmitoyl-2-linoleoyl-PC (PLPC) metabolism. High-density lipoproteins containing SAPC and PLPC tracers labeled in the sn-2 fatty acid with H-3 and C-14 isotopes, respectively, were administered. The rats were depleted of endogenous bile acids and infused via the ileum with individual bile acids that ranged widely in hydrophobicity. The half-lives for SAPC and PLPC in plasma were 48 and 57 min, respectively. Most of the H-3 activity that disappeared from plasma at 1 h was found in the liver in 1-palmitoyl-2-arachidonyl-PC, SAPC, and 1-oleoyl-2-arachidonyl-PC, indicating phospholipase A(1) hydrolysis of plasma SAPC forming 2-arachidonyl-lysophosphatidylcholine, which was reacylated in the liver. Plasma PLPC also underwent phospholipase A(1) hydrolysis, as reported previously. The fraction of H-3 dose that accumulated in plasma cholesteryl arachidonate was two- to threefold higher than the fraction of C-14 dose in cholesteryl linoleate. Multicompartmental models for SAPC and PLPC were developed that included lysophosphatidylcholines and cholesteryl esters. Bile acids did not influence plasma PC metabolism. Lecithin-cholesterol acyltransferase and phospholipase A(1) (hepatic lipase) hydrolysis accounted for greater than or equal to 90% of the SAPC and PLPC that disappeared from plasma; SAPC and PLPC are comparable as substrates for hepatic lipase, but SAPC is preferred by lecithin-cholesterol acyltransferase.