Altitude hypoxia is a major challenge to the blood O2 transport system, and adjustments of the blood-O2 affinity might contribute significantly to hypoxia adaptation. In principle, lowering the blood-O2 affinity is advantageous because it lowers the circulatory load required to assure adequate tissue oxygenation up to a threshold corresponding to about 5,000 m altitude, whereas at higher altitudes an increased blood-O2 affinity appears more advantageous. However, the rather contradictory experimental evidence raises the question whether other factors superimpose on the apparent changes of the blood-O2 affinity. The most important of these are as follows: (1) absolute temperature and temperature gradients within the body; (2) the intracapillary Bohr effect; (3) the red cell population heterogeneity in terms Of O2 affinity; (4) control of altitude alkalosis; (5) the possible role of hemoglobin as a carrier of the vasodilator nitric oxide; (6) the effect of varied red cell transit times through the capillaries.
|Titolo:||Oxygen transport in blood at high altitude : role of the hemoglobin-oxygen affinity and impact of the phenomena related to hemoglobin allosterism and red cell function|
|Autori interni:||SAMAJA, MICHELE (Primo)|
GUAZZI, MARCO (Penultimo)
|Parole Chiave:||Altitude hypoxia; Hemoglobin allosterism; Oxygen equilibrium curve; Red cell function|
|Settore Scientifico Disciplinare:||Settore BIO/10 - Biochimica|
Settore MED/11 - Malattie dell'Apparato Cardiovascolare
|Data di pubblicazione:||2003|
|Appare nelle tipologie:||01 - Articolo su periodico|
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