Le lipoproteine a bassa densità umane sono perossidate dai radicali liberi con reazioni a catena innescate dal radicale superossido.

Translated title of the contribution: Human low-density lipoproteins are peroxidized by free radicals via chain reactions triggered by the superoxide radical

C. Napoli, G. Ambrosio, G. Palumbo, P. P. Elia, M. Chiariello

Research output: Contribution to journalArticlepeer-review

Abstract

Low-density lipoproteins (LDL) oxidized by oxygen radicals (OR) are a potent atherogenic stimulus. Chemically modified LDL are internalized by macrophages via a specific cell surface receptor that was termed the scavenger receptor, and may induce foam cells transformation. A free radical is any chemical species that has an unpaired electron. This property renders it highly chemically reactive. When a radical reacts with a non radical another free radical is generated. This characteristic enables radicals to trigger chain reactions. Oxygen radicals are: superoxide anion (.O2-), hydroxyl radical (.OH) and hydrogen peroxide (H2O2). It is unknown whether LDL are modified via direct lipid oxidation by OR, or whether LDL are subsequently oxidized via chain reactions after initial OR attack. To distinguish between these 2 mechanisms, LDL were exposed to OR formed by xanthine/xanthine oxidase (X/XO). Peroxidation was measured from malonyldialdehyde (MDA) levels. Parallel experiments were performed in presence of the superoxide radical scavenger superoxide dismutase (SOD; 330 U/ml), or the hydrogen peroxide scavenger catalase (CAT; 1000 U/ml), or by adding the chain-reaction inhibitor butylhydroxytoluene (BHT; 1 mM) at selected time points. SOD, but not CAT prevented LDL peroxidation, indicating an obligatory role for superoxide radicals. Superoxide generation in this model lasts only a few minutes, however, MDA levels continued to increase over several hours. Furthermore, this phenomenon was blocked when BHT was added at various times after X/XO. These data show that LDL peroxidation is triggered by initial OR generation but then involves chain reactions which do not require continuous exposure to OR.(ABSTRACT TRUNCATED AT 250 WORDS)

Translated title of the contributionHuman low-density lipoproteins are peroxidized by free radicals via chain reactions triggered by the superoxide radical
Original languageItalian
Pages (from-to)527-532
Number of pages6
JournalCardiologia
Volume36
Issue number7
Publication statusPublished - Jul 1991

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine

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