Hematopoiesis in the grey collie dog. Studies of the regulation of erythropoiesis

Abstract

Hematopoiesis in the grey collie dog undergoes periodic fluctuations which involve reticulocytes, granulocytes, platelets, lymphocytes, and monocytes. This syndrome is inherited in an autosomal recessive manner and can be transmitted or abolished by appropriate bone marrow transplantation experiments, thus demonstrating this to be a primary marrow defect. Investigation of humoral regulation in this setting indicated that serum erythropoietin (ESF) also underwent cyclic fluctuation and that shortly after the increase and peak in serum ESF levels recognizable red cell precursors appear in the marrow. Erythropoiesis in the grey collie was reciprocally related to the blood O2 carrying capacity. With phlebotomy, ESF activity and reticulocytes increased but continued to cycle, while hypertransfusion eliminated reticulocyte production completely. Neither phlebotomy nor hypertransfusion altered the underlying cycle time (11-12 days) nor influenced the peaks of peripheral blood granulocytes. Thus, in these experiments, no direct evidence of competition between reticulocyte and granulocyte production was observed. In vitro studies of canine hemoglobin synthesis failed to demonstrate evidence of an inhibitor to ESF. These results indicate that periodic fluctuation of serum ESF is an integral part of the grey collie syndrome and are most consistent with some form of feedback regulation of ESF production. (30 references.)