the effect of altitude and hypoxia on the renin-angiotensin-aldosterone system is interesting for many reasons. As a physician and mountaineer I have been puzzled for many years by the etiology of acute mountain sickness, especially high-altitude pulmonary edema (HAPE). A derangement of fluid homeostasis produced indirectly by hypoxia appeared to be one characteristic. The time lag of 6–24 h between exposure to hypoxia and the onset of symptoms suggests that hypoxia may stimulate a hormonal response which over this time course could upset fluid homeostasis enough to cause symptoms. For a time we considered the antidiuretic hormone, but, although levels are raised in cases of HAPE (4), this is more likely a result than a cause of the condition. Case reports of HAPE persistently stress the importance of strenuous exertion in the formation of this condition. We therefore decided to first study the effect of exercise typical of mountaineers on fluid balance.
KeywordsPlasma Renin Activity Acute Mountain Sickness Aldosterone System Plasma Aldosterone Concentration Fluid Homeostasis
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