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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.

Additional information regarding the development of symptomatology subscales for the measurement of Acute Mountain Sickness (AMS) is presented. High item intercorrelations and strong factor loadings of items comprising symptom clusters (i.e., Arousal Level, Somatic Discomfort, Tired, and Mood) support the previously reported breakdown of the General High Altitude Questionnaire (GHAQ) into subscales. Rapid transition from low to high altitude resulted in an increase of these symptomatology subscale scores. Several subscale differences were also noted between Phenformin and Placebo Ss at low altitude. Such subscale measures could provide improved estimates of symptomatology, useful in assessing the effectiveness of various treatments intended to ameliorate AMS.