Sympathoadrenal response to hypoxia

Summary

The effect of hypoxia on the sympathoadrenal system of man was investigated by measuring the epinephrine, norepinephrine, and hydroxymethoxymandelic acid excretion of healthy adults confined to a low pressure chamber simulating 3000–4000 m of altitude. It was found that norepinephrine excretion remained essentially the same as at sea level conditions, but epinephrine and hydroxymethoxymandelic acid excretion increased significantly during exposure to low oxygen tension. In an earlier study at real high altitude (Dutch Monte Rosa expedition, 1963, 4560 m) a reversed excretion pattern was observed, i.e. norepinephrine excretion increased significantly with no change in epinephrine excretion. It was suspected, on the basis of evidence found in the literature, that the different nature of the physical and particularly emotional stress factors operating at real and at simulated high altitude might be responsible for the different pattern of catecholamine excretion. Subsequent experiments performed in the low pressure chamber at sea level conditions (“mock” runs) showed a similar response as in the low pressure chamber at reduced pressure which pointed to the importance of emotional facotrs during confinement to the chamber. Some other factors of possible importance in daily life which might affect the results of this study were also investigated and it was found that consumption of moderate amounts of coffee as well as moderate smoking did not cause increased excretion of catecholamines or hydroxymethoxymandelic acid.