The primary objective of the work described in this thesis was
to investigate some of the effects of chronic oxygen toxicity in
mammals. This thesis describes in vivo changes in certain metabolites
and enzymes following the exposure of mice and rats to increased
concentrations of oxygen at atmospheric pressure.
The introductory section reviews the historical background to
oxygen toxicity, delineates its two forms and describes their
aetiology. The physical and chemical properties of oxygen which
contribute to its unusual reactivity are discussed, together with
the reactive species of oxygen which may be responsible for its
toxicity. To complete the introduction, the known effects of oxygen
on metabolism are reviewed.
In order to pursue these studies it was necessary to design an
apparatus capable of providing a controlled high oxygen atmosphere.
Its construction and operation is described.
Results obtained indicated that the levels of the protective
enzymes superoxide dismutase and catalase varied in lung, liver and
brain of mice following exposure to increased oxygen levels.
Overall protein levels were also found to vary, so an experiment
involving a polyacrylamide gel separation was performed to reveal
any qualitative differences. Another experiment monitored the changes
in free amino acids in brain, liver, lung and muscle. A few
possible deviations from normal were detected but these changes
were not consistent between the tissues studied.
Results are presented of the changes in some gross physical
parameters and the effect of 3 prostaglandin inhibitors on these
in vivo changes. Other experiments revealed the changes in
haematocrit,
in retinol and in haemoglobin levels.
For comparative purposes some of the above measurements were
also applied to samples of body fluids from men suffering a mild
experimental oxygen toxicity.
The relevance of these results to the toxic effects of oxygen
in mammals is discussed
