Catecholamine levels in hypoxia-lnduced acute mountain sickness.
Enhanced sympathoadrenal activity has been implicated in the pathogenesis of acute mountain sickness (AMS). This study was designed to examine the time course of circulating catecholamines in individuals with and without AMS.


METHODS
Subjects were low-altitude residents (10 men, 8 women) who had not been exposed to altitude within the previous 2 mo. They breathed 12% O2 (hypoxia equivalent to 4600 m altitude) for 8 h while seated at rest. AMS was evaluated using Lake Louise scores (LLS) at 0, 1, 3, 5, and 7 h of exposure using a threshold of 3 to define AMS. Blood samples were collected to measure arterial blood gases and oxygen saturation as well as arterial and venous epinephrine (A-EPI and V-EPI) and norepinephrine (A-NE and V-NE).


RESULTS
Eight subjects (44%) developed AMS at some time during the experiment. Blood gases showed no significant difference between subjects with or without symptoms (AMS+ and AMS-, respectively). However, AMS+ subjects showed significantly greater concentrations of A-EPI over the 8 h without any between-group difference in V-EPI. Levels of A-NE were significantly higher at baseline and during the first hour of hypoxia in subjects who later developed AMS. V-NE increased significantly over time among all participants with no difference between groups.


CONCLUSIONS
These findings suggest a possible physiological marker for individuals who may be relatively susceptible to AMS and provide additional insight into the sympathoadrenal response to acute hypoxia.
Kamimori
Gary H
GH
Department of Behavioral Biology, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA. gary.kamimori@us.army.mil
Ryan
Edward J
EJ
Otterstetter
Ronald
R
Barkley
Jacob E
JE
Glickman
Ellen L
EL
Davis
Harry Q
HQ
D000293:Adolescent; D000328:Adult; D000532:Altitude Sickness / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D001784:Blood Gas Analysis; D004837:Epinephrine / Q000097:blood*; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000097:blood* / Q000503:physiopathology; D008297:Male; D009638:Norepinephrine / Q000097:blood*; D012720:Severity of Illness Index; D055815:Young Adult
D015415:Biomarkers; D009638:Norepinephrine; D004837:Epinephrine