Evaluation of erythropoietic potential during pathogenesis of the Shay chloroleukemia.

To evaluate the erythropoietic potential of rats during pathogenesis of Shay chloroleukemia (SCL), SCL animals were exposed to hypoxia initiated within two hours postinduction of SCL. Increases in hematocrit (HCT) occurred in both SCL and nonleukemic controls during the first seven days of exposure. This was followed by declines in HCT in hypoxic SCL rats similar to that observed in nonhypoxic SCL animals. HCT of nonleukemic controls remained elevated throughout hypoxic exposure. Results suggested that in SCL, erythropoietic homeostatic response mechanisms are functional prior to terminal phases of this disease, whereas anemia-producing mechanisms exceed maximum erythropoietic capacity of these animals during later stages of SCL. The HCT of most SCL rats exposed to hypoxia did not fall below 40% before death. This was in contrast to nonhypoxic SCL animals, which became severely anemic in terminal stages. No survival value was observed despite maintenance of red cell mass at or above normal. The pathogenesis of this leukemia was independent of the leukemic animal's erythropoietic potential.