An increase in brain superoxide dismutase activity was found in rats exposed to high altitude hypoxia (7000 m, 30 min daily for five days) and ascorbic acid treatment (1 mg.g'1 daily s.c.) while no significant change was observed after high altitude hypoxia or ascorbic acid alone.
Quinidine-like immunoreactivity (Abbott TDx Quinidine fluorescence polarization immunoassay) was measured in blood serum of control rats and rats exposed to hypoxia in a hypobaric chamber (7 500 m for one hour). The mean "quinidine" levels (mean±S.D.) were 0.159±0.058 and 0.260±0.110 («mol quinidinq/1 serum), respectively (p<0.01).
Control (physiological saline treated) and ascorbic acid (AA) treated (1 mg . g'1 b.w. one hour before exposure) 18-day-old rats were exposed for 1 hour to high altitude in a hypobaric chamber and the mean lethal altitudes were calculated. AA displayed a protective effect, so that in two identical experiments the mean lethal altitude was 10 900 and 10 150 m in controls, while it was 11 500 and 11 450 m in AA treated animals.