Human llamas: adaptation to altitude in subjects with high hemoglobin oxygen affinity.
To assess the adaptive value of the right-shift of the oxyhemoglobin dissociation curve (decreased affinity for oxygen) observed in humans upon altitude exposure, the short-term physiologic responses to altitude-induced hypoxia were evaluated in two subjects with a high oxygen affinity hemoglobin (Hb Andrew-Minneapolis) and in two of their normal siblings. In striking contrast to normal subjects, at moderately high altitude (3,100 m) the high affinity subjects manifested: (a) lesser increments in resting heart rate; (b) minimal increases in plasma and urinary  erythropoietin; (c) no decrement in maximal oxygen consumption; and (d) no thrombocytopenia. There was no difference between subject pairs in 2,3-diphosphoglycerate response to altitude exposure. These results tend to contradict the belief that a decrease in hemoglobin oxygen affinity is of adaptive value to humans at moderate altitudes. Rather, they support the hypothesis that, despite disadvantages at low altitude, a left-shifted oxyhemoglobin dissociation curve may confer a degree of preadaptation to altitude.
D000222:Adaptation, Physiological; D000293:Adolescent; D000531:Altitude; D001772:Blood Cell Count; D001792:Blood Platelets; D002648:Child; D004163:Diphosphoglyceric Acids / Q000097:blood; D004920:Erythropoiesis; D004921:Erythropoietin / Q000097:blood / Q000652:urine; D005260:Female; D006339:Heart Rate; D006454:Hemoglobins / Q000378:metabolism*; D006455:Hemoglobins, Abnormal / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D000860:Hypoxia / Q000503:physiopathology; D008297:Male; D010100:Oxygen / Q000097:blood*; D010108:Oxyhemoglobins / Q000378:metabolism
D004163:Diphosphoglyceric Acids; D006454:Hemoglobins; D006455:Hemoglobins, Abnormal; D010108:Oxyhemoglobins; D004921:Erythropoietin; D010100:Oxygen