Hypobaric Hypoxia: Within-Subject Transition Effects in Albino Rats

The effect of rapid hypobaric transition (1 hr.) upon water consumption, food consumption, body weight, feeding activity and spontaneous activity of albino rats was studied using a within-subject design. Transition from 635 ± 5 mm. Hg. (5,000 ft.) to 455 ± 5 mm. Hg. (14,000 ft.) induced temporary hypophagia, hypodipsia and concomitant weight loss; gradual recovery occurred during the exposure period; return to 635 ± 5 mm. Hg. after 7 days abruptly (≤ 24 hr.) alleviated these effects. Alterations in feeding activity (time-in-foodwell) during the off portions of the light cycle paralleled food intake changes. No reliable changes in spontaneous activity as a function of hypobaric transition were noted. Results were interpreted as suggestive of hypothalamic and frontal cortex involvement in hypoxia-induced behavioral shifts.