Body fluid and hematologic changes in the toad exposed to 48 h of simulated high altitude

Body fluid and hematologic changes were found in three groups of adult male toads that had been exposed to 48 h of continuous simulated altitudes of 12,000, 18,000, and 24,000 ft, respectively. Erythrocyte counts and hematocrit ratios were increased significantly in all the high-altitude-exposed animals compared with the control group of animals kept at sea level, whereas the hemoglobin concentrations were significantly increased only in the 18,000- and 24,000-ft-exposed animals. Exposure to high altitude generally caused a reduction of plasma volume, blood volume, extracellular fluid volume, and total body water. These reductions were markedly lower in the animals exposed to 24,000 ft. These simulated high-altitude effects on body fluids and hematology in the toad (Bufo melanostictus) were compared with those of the rat, birds, and humans acutely acutely exposed at various high altitudes and were found to be qualitatively similar.