The Role of Orexin-A and HIF-1 Responses in Acute Mountain Sickness

Acute mountain sickness (AMS) caused by rapid ascent to altitudes higher than 2500 m has complex pathophysiological conditions. Therefore, the aim of the present study was to investigate hypoxia related factors in individual susceptible to acute mountain sickness. 21 healthy subjects (mean age 31.7±8.5 year) participated in this study. Fasting blood samples were collected from antecubital vein (sea level) 1 hour and 24 hours after rapid ascent to an altitude of 3550 m by a gondola lift. HIF-1 and Orexin-A were measured by ELISA method. AMS status was measured by the Lake Louise Scoring 6 hours after the exposure to a high altitude. Lake Louise Scoring showed that 11 subjects got AMS after the exposure to a high altitude (LLS≥4). The results showed that Orexin-A and HIF-1 at sea level were higher in AMS-susceptible subjects than AMS-resistant subjects. But Orexin-A and HIF-1 responses were almost higher in AMS-susceptible subjects than AMS-resistant subjects. Orexin-A and HIF-1 at sea level had an inverse relationship with AMS. An increase in these proteins in AMS-susceptible subjects was drastically higher than AMS-resistant subjects after exposure to altitude.