NO Reaction with Oxidized Lipids and LDL

FIGURE I Free radical interactions with lipoproteins or cells. LO, Lipoxygenase O j, superoxide anion ONOO , peroxynitrite H2O2, hydrogen peroxide XO, xanthine oxidase NO, nitric oxide NOS, nitric oxide synthase. 

FIGURE 2 The influence of authentic nitric oxide (-NO) infusion on xanthine oxidase (XO)-dependent liposome oxidation. PC liposomes (6.6 mg/ml) were oxidized with 1.5 mil/ ml XO, 10 mM acetaldehyde, and 100 /aM EDTA-Fe. Infusion of -NO (0.1, 0.25, 0.5, 0.7, 1, 2, and 3 /uM/min) was performed simultaneously. The open circle represents incubation of the reaction mixture in the absence of XO. The data represent the mean of duplicate determinations and were representative of three separate experiments. TBA, 2-Thiobarbituric acid. [Adapted from Rubbo et al. (1994a) with permission.] 

When LOOM species prepared by SLO oxidation of either linoleic or linolenic acid were incubated with bovine serum albumin, fluorescent products having excitation and emission spectra similar to those of oxidized LDL were observed (Fig. 6). From this, it has been proposed that after homolytic cleavage of LOOH to the more reactive LOO-, a concerted reaction occurs between LOO- and polypeptide amino groups to yield fluorescent adducts without prior LOOH fragmentation to aldehydes or other, more stable, products (Fruebis et al., 1992). During LDL or cell membrane oxidation 

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