First 11 pages of thesis. - OPUS - Universität Würzburg

ate at which superoxide is degraded by SOD (2x10 9 M -1 sec -1 ). Further
dismutation of superoxide by SOD can occur only if the latter enzyme is present
in the same compartment in which superoxide is produced. In addition to being
a significant source of eNOS mediated nitric oxide production, the endothelium
is also a significant source of superoxide production in atherosclerotic vessels 70 .
Since under these conditioms nitric oxide and superoxide are produced in the
same cellular compartment, i.e., the endothelial cell, they can immediately react
to form peroxynitrite. Peroxynitrite is a strong oxidant which alters the function
of biomolecules by protein nitration and lipid peroxidation 71 with secondary
tissue injury 39, 40 . Subintimal lipoprotein oxidation by peroxynitrite may initiate
the formation of fatty streaks and subsequent plaque development 39 .
Peroxynitrite may also contribute to endothelial cell dependant vascular
oxidation.
Figure 3: Proposed functional role of nitric oxide and superoxide in normal and atherogenic
conditions, respectively.
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