Hemoglobinemia in rats exposed to high altitude is not due to an overload of catabolic mechanisms
Smith, R.P.; Kruszyna, R.; Ou, L.C.
Aviation Space and Environmental Medicine 50(1): 9-13
1979
ISSN/ISBN: 0095-6562 PMID: 420674 Document Number: 139298
When male rats are exposed to a simulated altitude of 18,000 ft (5490 m) for as little as 10 days, a unique hematologic condition ensues.sbd.a hemoglobinemia in the face of an elevated hematocrit. The hypothesis that this hemoglobinemia is secondary to an overloading of Hb catabolic pathways was tested. The capacity of male rats to catabolize Hb was challenged by acute hyper-transfusion, by chronic Co injections and by splenectomy in combination with altitude exposure. None of these treatments mimicked or exacerbated the hemoglobinemia of altitude exposure, suggesting that it is not due to a stress on the Hb catabolic reserve. A remaining viable hypothesis to be tested is that the hemoglobinemia is secondary to ineffective hematopoiesis. The spleen does not appear to be obligatory for either the hemoglobinemia or the polycythemia of the altitude-exposed rat. Both altitude exposure and chronic Co treatment resulted in increases in red cell 2,3-diphosphoglycerate decreases in body weight, and splenic hypertrophy. The latter 2 changes were more prominent in males exposed to altitude, but not males given chronic Co injections. In male rats, altitude exposure resulted in a significant decrease in the liver/body weight ratio whereas Co had no effect on liver weight in either sex.