Blood destruction in the polycythemia induced by hypoxia

The hemoglobin catabolism during the development and during the disappearance of polycythemia induced by hypoxia was studied by measuring the totalcirculating hemoglobin and the daily bile pigment excretion in bile-fistula dogsbefore, during, and after prolonged periods of exposure to 20,000 feet simulatedaltitude.

1. The inscreased erythropoiesis during the first weeks of altitude exposure wasaccompanied by a signiflcant increase in bile pigment output. The possible sourcesof this pigment excretion are discussed.

2. The life spans of the red cells during altitude exposure was found to be about115 days. No differences were observed in the longevity of the cells in animals atground level and at altitude.

3. The normalization of the polycythemic blood levels took place within sixto eight weeks after returns to ground level, and was achieved by the combinedeffect of a depressed erythropoiesis and of an increased blood destruction. Theincrease in red cell destruction observed under these conditions demonstratesthe existence of an "active" mechanism of blood destrunction by which the organism is able to destroy normal blood cells before their life span is exhausted. Thisincreased red cell destruction, however, accounted for only 21 to 39 per cent ofthe hemoglobin which disappeared from circulation after return to ground level.The major part of the normalization of altitude polycythemia was brought aboutby a temporary depression of erythropoiesis which was estimated to amount to30 or 40 per cent of the normal cell production in the six weeks after the discontinuation of the altitude exposure.

Submitted on September 15, 1951 Accepted on October 25, 1951