Abstract：
:Conditions leading to oxidation of LDL in vivo are still unknown. While the occurrence of oxidized lipoproteins and catalytic free iron in advanced atherosclerotic lesions has been demonstrated, the origin of both is unclear. In vivo, iron metabolism is tightly regulated by iron-binding proteins that ensure that virtually no free iron exists. We examined whether physiological events such as lipolysis might reduce pH, facilitate iron release from transferrin (Tf), and promote low density lipoprotein (LDL) oxidation. Lipolysis is brought about by lipoprotein lipase (LpL), a triglyceride hydrolase present on endothelial cell surfaces and in atherosclerotic lesions. LpL hydrolysis of Intralipid lowered pH from 7.40 to 7.00 in 10% human serum and from 7.40 to 6.88 in phosphate-buffered saline. Similar decreases in pH were also observed when very low density lipoproteins were hydrolyzed by LpL. Lipolysis was accompanied by a 2-fold increase in the release of 59Fe from Tf. Tf binding to subendothelial matrix (SEM), a site of key events in atherosclerosis, increased 2-fold as the pH decreased from 7.40 to 6.00. More free iron also bound to SEM as the pH decreased below 7.40. We next tested whether a reduction in pH promotes LDL oxidation. More oxidation products were found in LDL incubated at low pH for 24 h in 10% human serum. Malonaldehyde contents (nmol/mg protein), measured as TBARS, were 7.11 +/- 0.34 at pH 7.40, 7.65 +/- 0.49 at pH 7.00, 9.00 +/- 1.18 at pH 6.50, and 11. 54 +/- 0.63 at pH 6.00. Based on these results, we hypothesize that lipolysis-induced acidic conditions enhance iron release from Tf and increase formation of oxidized LDL.
journal_name
J Lipid Resjournal_title
Journal of lipid researchauthors
Balagopalakrishna C,Paka L,Pillarisetti S,Goldberg IJkeywords:
subject
Has Abstractpub_date
1999-07-01 00:00:00pages
1347-56issue
7eissn
0022-2275issn
1539-7262journal_volume
40pub_type
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journal_title：Journal of lipid research
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journal_title：Journal of lipid research
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journal_title：Journal of lipid research
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journal_title：Journal of lipid research
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journal_title：Journal of lipid research
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journal_title：Journal of lipid research
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journal_title：Journal of lipid research
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更新日期：1981-08-01 00:00:00
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更新日期：1987-08-01 00:00:00
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更新日期：1976-09-01 00:00:00
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journal_title：Journal of lipid research
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更新日期：1979-02-01 00:00:00
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journal_title：Journal of lipid research
pub_type： 杂志文章
doi：
更新日期：1996-06-01 00:00:00
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更新日期：1973-09-01 00:00:00
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journal_title：Journal of lipid research
pub_type： 杂志文章
doi：
更新日期：1996-08-01 00:00:00
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journal_title：Journal of lipid research
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doi：
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journal_title：Journal of lipid research
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