THE ESSENTIAL
- During an ascent, Sherpas exhibited greater and/or faster respiratory and renal acclimatization, which resulted in a fully compensated pH at 4,300 meters.
- During the expedition, people living in the plains at 1,400 meters were alkalemic, that is, they had an increase in blood pH due to alkalosis.
- According to Canadian researchers, these results are beneficial for physiology as a whole.
“Exposure to high altitude imposes a challenge to blood oxygenation and acid-base balance. A sustained and increased hypoxic ventilatory response protects oxygenation through ventilatory acclimation, but causes hypocapnia (a decreased amount of carbon dioxide in arterial blood) and respiratory alkalosis Renally mediated compensatory metabolic acidosis then corrects the pH towards baseline values, with a high degree of variability. “The differential renal compensation between the inhabitants of the lowlands and the inhabitants of the Tibetan highlands (the Sherpas) during ascension was not known until now”, indicated researchers from Mount Royal University (Canada).
Renal acclimatization of Sherpas is greater and faster at 4,300 meters
In a study, published in the journal Proceedings of the National Academy of Sciencesthey decided to evaluate respiratory and renal acclimation between unacclimatized, age- and sex-matched groups of lowland dwellers and Tibetan highlanders, namely Sherpas, during a gradual climb of 4,300 meters in the Nepalese Himalayas. Specifically, the team focused on the acid-base acclimation reactions of the blood before, at 1,400 meters, and after the eighth and ninth days of the expedition in both groups.
According to the results, people living in the plains had significantly lower carbon dioxide partial pressure and ventilatory function. As for their pH, it was only high at 1,400 meters, “which suggests respiratory alkalosis and only partial renal compensation.” In contrast, Sherpas had slightly lower carbon dioxide partial pressure and ventilatory function than usual, but unchanged pH. This indicates “complete renal compensation” at 4,300 meters.
Renal function: “selective pressure on the populations of the Tibetan highlands”
“This study provides insight into the interplay between ancestry and physiological mechanisms contributing to high altitude acclimation, which could indicate selective pressure on ancestral populations of the Tibetan highlands with respect to kidney function during acclimatization”, said Trevor Day, author of the research, who believes these results are beneficial for physiology as a whole.
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