One of the key features of Sherpas, which provide them with adaptation to high-altitude conditions, was better control over the circulation of blood.
Representatives of a small number of Sherpa people have been living in the vicinity of Jomolungma for centuries and serve as permanent guides for those wishing to rise to the top of the world. To life at high altitude they are adapted, apparently, better than anyone on Earth, including other mountaineers, which makes Sherpas objects of constant interest of scientists.
Among the interesting riddles of their physiology is the stability of the number of erythrocytes in the blood. Both in ordinary Europeans and in the Andeans, the organism reacts to a decrease in the oxygen content and a fall in atmospheric pressure (hypobaric hypoxia) by an increase in the number of red blood cells, which allows one to bind more oxygen from the inhaled air. However, in Sherpas this does not happen: that at sea level, which at an altitude of kilometers the count of red blood cells remains the same.
This issue interested Geraldine Clough (Geraldine Clough) of the University of Southampton and her colleagues working within the framework of the program Xtreme Everest 2 and studying various aspects of life at high altitudes and extreme physiology. Their article is published in the journal Experimental Physiology.
In the experiments, 83 lowlanders participated, as well as 61 Sherpa, who made 11-day ascents to the height of the base camp (5300 meters) on the way to Everest. Preliminary blood samples were obtained in London (50 meters above sea level) and in Kathmandu (1300 meters). It was found that the amount of hemoglobin in the blood of Sherpas did not increase with the climb, but the vasomotor function was enhanced, ensuring efficient supply of tissues with oxygen.
In fact, a simple increase in the number of erythrocytes has an unpleasant side, increasing the viscosity of the blood, which makes it difficult to circulate and work the heart, and is fraught with obstruction of the vessels of the lungs. So one of the adaptations of Sherpas was the ability to increase blood flow to the needy tissues and organs without increasing the hemoglobin content and unpleasant side effects.