Exhaled nitric oxide in ethnically diverse high-altitude native populations: A comparative study

Area of Science:

• Human physiology
• High-altitude adaptation
• Respiratory research

Background:

• High-altitude natives often display elevated nitric oxide (NO) in lungs, suggesting a role in adapting to low oxygen environments (hypobaric hypoxia).
• Previous research indicated this elevated NO might be a universal adaptive trait among high-altitude populations.

Purpose of the Study:

• To investigate if elevated exhaled nitric oxide (NO) is a universal adaptive trait in high-altitude native populations.
• To compare NO concentrations in diverse highland populations with sea-level controls.

Main Methods:

• Recruited Tawang Monpa (Tibetan-derived) and Peruvian Quechua (Andean) high-altitude natives.
• Included sea-level born and migrant Quechua subgroups and a lowland European ancestry control group.
• Measured fraction of exhaled NO concentrations using a NIOX NIMO device.

Main Results:

• Partial pressure of exhaled NO (PENO) was significantly lower in high-altitude residents (Tawang Monpa and Peruvian Quechua at altitude) compared to sea-level groups.
• No significant difference in PENO was observed between the Tawang Monpa and high-altitude Peruvian Quechua groups.
• PENO levels in high-altitude residents were substantially lower than in sea-level controls and sea-level born/migrant Quechua.

Conclusions:

• Findings contradict the hypothesis that high exhaled NO is a universal adaptation to hypobaric hypoxia in high-altitude natives.
• Lower PENO in high-altitude populations suggests NO may not play the hypothesized adaptive role in offsetting low oxygen.
• The study indicates that high exhaled NO is not a consistent trait across diverse highland populations.