This was sourced from the Cleveland Clinic Newsletter. The Nitric Oxide is an important item in moving oxygen in the blood. These people exist at 14,000' levels.
January 2008
Could High Nitric Oxide Production Contribute to Increased Oxygen in the Blood?
How can some people live at high altitudes and thrive while others struggle to obtain enough oxygen to function?
The answer for Tibetans who live at altitudes around 14,000 feet is increased nitric oxide (NO) levels. High levels of NO circulate in various forms in the blood and produce the physiological mechanisms that cause increased blood flows that maintain oxygen delivery despite hypoxia ? low levels of oxygen in the ambient air and the bloodstream.
Researchers from the Institute's Department of Pathobiology participated in a report by Case Western Reserve University that Tibetans have 10 times more NO and more than double the forearm blood flows of low-altitude dwellers.
?NO is critical for oxygen transport and delivery in this chronically hypoxic population,? write the researchers.
The low barometric pressure of high altitudes generally causes low arterial oxygen content among Tibetans, yet the researchers have found that Tibetans consume oxygen at normal rates.
?We asked how that could be done,? said Cynthia Beall, Ph.D., Adjunct Staff in Pathobiology and a Professor of Anthropology at Case Western Reserve University. Over the past two decades, she has become a leading researcher in the studies of high-altitude adaptation in different populations in Ethiopia, South America and Tibet.
Dr. Beall collected the blood samples and blood flow readings from the forearms of 88 Tibetans during a 2002 research trip that was funded by the National Science Foundation.
The blood flow data and blood samples were brought back to the United States where Serpil Erzurum, M.D., Chair, Pathobiology, and members of her laboratory analyzed the information. For comparison, the two scientists collected the same information from 50 near-sea-level dwellers from the United States that participated in the study at the General Clinical Research Center at Cleveland Clinic.
Blood flow is determined by the length, number and width of the diameter of blood vessels. These numbers are determined partly by NO, which is a dilator of the vessels, and prevents high blood pressure that would result from increased blood flows in restricted blood vessels. NO also helps in the release of oxygen to tissues.
NO reacts in the blood to produce nitrite, nitrosothiol proteins and a -nitrosyl hemoglobin and can be used as an indicator of NO production. To confirm the increases in NO, the researchers subjected the Tibetan samples to sensitive high performance liquid chromatography, where the results verified the 10-fold increase of NO in the blood.
From the analysis, the researchers also recognized another population difference: Tibetan women were found to have higher nitrite and lower nitrate levels than those of Tibetan men, whereas no gender differences were found in sea-level dwellers.
The combined increased NO and blood flow levels resulted in double the amount of oxygen delivered to the capillary beds in the Tibetans' arms.
The researchers hypothesize that Tibetans have a genetic mutation that allows high NO production. Genetic studies and comparable data on sea-level populations living at high altitude would be needed to test that hypothesis.
The study's other researchers were Sudhakshina Ghosh, Allison Janocha, Weiling Xu, Dennis Stuehr, Ph.D., and Jesus Tejero, Pathobiology; S. Bauer, Martin Feelisch, Ph.D., and Nathan Bryan from the Whitaker Cardiovascular Institute at Boston University School of Medicine; and Craig Hemann and Charles R. Hille, Ph.D., from Ohio State University. The findings were reported in the article ?Higher Blood Flow and Circulating NO Products Offset High-altitude Hypoxia Among Tibetans? in the Proceedings of the National Academy of Sciences (www.pnas.org/, 2007;104:17593-17598).
Lraynak
January 2008
Could High Nitric Oxide Production Contribute to Increased Oxygen in the Blood?
How can some people live at high altitudes and thrive while others struggle to obtain enough oxygen to function?
The answer for Tibetans who live at altitudes around 14,000 feet is increased nitric oxide (NO) levels. High levels of NO circulate in various forms in the blood and produce the physiological mechanisms that cause increased blood flows that maintain oxygen delivery despite hypoxia ? low levels of oxygen in the ambient air and the bloodstream.
Researchers from the Institute's Department of Pathobiology participated in a report by Case Western Reserve University that Tibetans have 10 times more NO and more than double the forearm blood flows of low-altitude dwellers.
?NO is critical for oxygen transport and delivery in this chronically hypoxic population,? write the researchers.
The low barometric pressure of high altitudes generally causes low arterial oxygen content among Tibetans, yet the researchers have found that Tibetans consume oxygen at normal rates.
?We asked how that could be done,? said Cynthia Beall, Ph.D., Adjunct Staff in Pathobiology and a Professor of Anthropology at Case Western Reserve University. Over the past two decades, she has become a leading researcher in the studies of high-altitude adaptation in different populations in Ethiopia, South America and Tibet.
Dr. Beall collected the blood samples and blood flow readings from the forearms of 88 Tibetans during a 2002 research trip that was funded by the National Science Foundation.
The blood flow data and blood samples were brought back to the United States where Serpil Erzurum, M.D., Chair, Pathobiology, and members of her laboratory analyzed the information. For comparison, the two scientists collected the same information from 50 near-sea-level dwellers from the United States that participated in the study at the General Clinical Research Center at Cleveland Clinic.
Blood flow is determined by the length, number and width of the diameter of blood vessels. These numbers are determined partly by NO, which is a dilator of the vessels, and prevents high blood pressure that would result from increased blood flows in restricted blood vessels. NO also helps in the release of oxygen to tissues.
NO reacts in the blood to produce nitrite, nitrosothiol proteins and a -nitrosyl hemoglobin and can be used as an indicator of NO production. To confirm the increases in NO, the researchers subjected the Tibetan samples to sensitive high performance liquid chromatography, where the results verified the 10-fold increase of NO in the blood.
From the analysis, the researchers also recognized another population difference: Tibetan women were found to have higher nitrite and lower nitrate levels than those of Tibetan men, whereas no gender differences were found in sea-level dwellers.
The combined increased NO and blood flow levels resulted in double the amount of oxygen delivered to the capillary beds in the Tibetans' arms.
The researchers hypothesize that Tibetans have a genetic mutation that allows high NO production. Genetic studies and comparable data on sea-level populations living at high altitude would be needed to test that hypothesis.
The study's other researchers were Sudhakshina Ghosh, Allison Janocha, Weiling Xu, Dennis Stuehr, Ph.D., and Jesus Tejero, Pathobiology; S. Bauer, Martin Feelisch, Ph.D., and Nathan Bryan from the Whitaker Cardiovascular Institute at Boston University School of Medicine; and Craig Hemann and Charles R. Hille, Ph.D., from Ohio State University. The findings were reported in the article ?Higher Blood Flow and Circulating NO Products Offset High-altitude Hypoxia Among Tibetans? in the Proceedings of the National Academy of Sciences (www.pnas.org/, 2007;104:17593-17598).
Lraynak