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  • 标题:Mechanisms involved in vitamin E transport by primary enterocytes and in vivo absorption
  • 本地全文:下载
  • 作者:Anwar, Kamran ; Iqbal, Jahangir ; Hussain, M. Mahmood
  • 期刊名称:JLR Papers In Press
  • 印刷版ISSN:0022-2275
  • 电子版ISSN:1539-7262
  • 出版年度:2007
  • 卷号:48
  • 期号:9
  • 页码:2028-2038
  • DOI:10.1194/jlr.M700207-JLR200
  • 出版社:American Society for Biochemistry and Molecular Biology
  • 摘要:It is generally believed that vitamin E is absorbed along with chylomicrons. However, we previously reported that human colon carcinoma Caco-2 cells use dual pathways, apolipoprotein B (apoB)-lipoproteins and HDLs, to transport vitamin E. Here, we used primary enterocytes and rodents to identify in vivo vitamin E absorption pathways. Uptake of [3H]{alpha}-tocopherol by primary rat and mouse enterocytes increased with time and reached a maximum at 1 h. In the absence of exogenous lipid supply, these cells secreted vitamin E with HDL. Lipids induced the secretion of vitamin E with intermediate density lipoproteins, and enterocytes supplemented with lipids and oleic acid secreted vitamin E with chylomicrons. The secretion of vitamin E with HDL was not affected by lipid supply but was enhanced when incubated with HDL. Microsomal triglyceride transfer protein inhibition reduced vitamin E secretion with chylomicrons without affecting its secretion with HDL. Enterocytes from Mttp-deficient mice also secreted less vitamin E with chylomicrons. In vivo absorption of [3H]{alpha}-tocopherol by mice after poloxamer 407 injection to inhibit lipoprotein lipase revealed that vitamin E was associated with triglyceride-rich lipoproteins and small HDLs containing apoB-48 and apoA-I. These studies indicate that enterocytes use two pathways for vitamin E absorption. Absorption with chylomicrons is the major pathway of vitamin E absorption. The HDL pathway may be important when chylomicron assembly is defective and can be exploited to deliver vitamin E without increasing fat consumption. Supplementary key words lipoproteins • tocopherol • HDL • chylomicrons • oleic acid Abbreviations: apoA-I, apolipoprotein A-I; FPLC, fast-performance liquid chromatography; IDL, intermediate density lipoprotein; MTP, microsomal triglyceride transfer protein; OA, oleic acid; P407, poloxamer 407; pIpC, polyinosinic-polycytidylic ribonucleic acid
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