The kinetics of hematopoiesis in the light horse III. The hematological response to hemolytic anemia.

The hematological response to acetylphenylhydrazine hemolytic anemia was studied in three standardbred horses. The lifespan of erythrocytes produced during the most severe phase of the anemia were measured with 75-selenomethionine and found to be 144 days as compared to the 139 day lifespan in response to hemorrhagic anemia or 155 days in normal standardbred horses measured previously using the same technique. The erythrocyte counts returned to initial values in 42 days (37, 34 and 54 days) a mean erythrocyte production of 6.4 times 10-12 erythrocytes/day. The mean hemoglobin production was 0.31 gm/kg body weight/day as compared to 0.11 gm Hb/kg/day previously observed in response to hemorrhagic anemia. The mean increase in erythrocyte mean cell volume was 12 mu-3 during the acute response phase to hemolytic anemia in contrast to the absence of a significant increase in the mean cell volume as previously observed during response to hemorrhagic anemia. Free Heinz bodies separated from erythrocytes during the acute phase could not be differentiated from platelets on the hemocytometer counting chamber with standard techniques.