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The effect of altitude chamber hypoxia of different intensity and duration on epinephrine and norepinephrine excretion was investigated. The hypoxia tolerance as a function of catecholamine excretion was also examined. At altitudes 5000 and 6500-7000 m the test subjects were kept for a short time and at 3500-4500 m for 24 hours. The subjects with high hypoxia tolerance showed an increased and those with low tolerance a decreased epinephrine excretion. The epinephrine excretion did not increase with the intensity and duration of the hypoxia effect. Variations in the norepinephrine excretion were insignificant in all tests.

Variations in coronary circulation, cardiac output and heart rate were examined by dopplerography in 14 test subjects kept in an altitude chamber. It was found that during acute hypoxia the effective coronary blood flow decreased distinctly prior to general circulatory disorders. It is recommended to monitor coronary circulation during altitude exposures.