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USE OF OXYGEN-18 ISOTOPE LABELING FOR MEASUREMENT OF OXIDATIVE STRESS
Citation:
Hatch, G. E. USE OF OXYGEN-18 ISOTOPE LABELING FOR MEASUREMENT OF OXIDATIVE STRESS. Presented at Society of Toxicology 42nd Annual Meeting, Salt Lake City, Utah, March 9-13, 2003.
Description:
Oxygen-18 (18-O) labeling provides a sensitive means for quantifying oxygen
binding that occurs during in vivo oxidations. Oxidants (ozone, nitrogen
oxides, hydrogen peroxide, etc.) are first synthesized using 18-O, then cells
or tissues are exposed to the labeled oxidants, after which the tissues can be
assayed for excess 18-O to indicate the extent of oxidation that occurred in
them (they can be stored frozen indefinitely). In addition to exposure to
labeled oxidants, animals can be exposed to 18-O2 gas at the same time they
are exposed to free radical generating toxicants (metal, CCl4, etc.) to yield an
estimate of "secondary oxidations." Separation of tissue fractions (protein,
lipid, DNA, etc.) provides individual assessment of oxidation in these pools,
yielding valuable information about mode of action of the oxidants studied.
Measurement of the elimination of 18-O in urine appears to provide a
quantitative assessment of tissue repair following oxidative injury. Since
18-O is not radioactive, it is easily used in human studies. We have used it to
compare human and animal ozone dose to target sites in the nose and lung.
Interactions between ozone and inhaled diesel particles have also been
elucidated using 18-O. Comparisons between 18-O measurements and more
traditional measures of oxidative stress indicate that the former method is
often more sensitive and less subject interferences and artifacts. However,
further work is needed to distinguish between pathological and "normal"
oxidations. In summary, use of oxygen-18 provides a new window from
which to view oxidative processes occurring in vivo.
This abstract is for a proposed presentation and does not necessarily reflect EPA policy.