Influence of Repeated Acute Thrombocytopenias on the Reappearance of Circulating Blood Platelets

Repeated experimental thrombocytopenia has been performed in three groups of dogs, at intervals of 2 days, 5-7 days, and 10 days. In the first two of these groups, the circulating thrombocytes reappear significantly more rapidly and the maximal platelet counts average respectively 138 per cent (p < 0.02) and 174 per cent (p < 0.001) of the peak observed after a single platelet depletion. If the thrombocytopenic stimulus is repeated at a 10-day interval, this modification in the rate of reappearance of platelets and in the platelet counts does not occur. It is concluded that platelet production induced by a single acute depletion does not represent the maximal medullary response and that thrombocytopoiesis can be further increased if the stimulus is repeated 2-7 days after a first one. Recovery curves after platelet depletion alone or followed by bleeding are similar, suggesting that thrombocytopoiesis is not influenced by a factor stimulating erythropoiesis.