The formation of bilirubin-14C was measured in rats given transfusions of red blood cells containing 14C-labeled hemoglobin heme. Per cent conversion of hemoglobin-14C to bilirubin was 4 times greater with transfusion of “stress” reticulocytes from rats responding to hemorrhage than with normal reticulocytes from unstimulated donors. When the increased number of labeled reticulocytes produced by hemorrhaged donors was also considered, the total magnitude of labeled bilirubin formation was almost 20 times higher with stress as compared to normal reticulocytes. The findings were not influenced by splenectomy of either donor or recipient rats, iron loading of donors, or bleeding of recipients. However, bilirubin-14C formation fell off progressively as studies were performed at longer intervals after erythroid stimulation.


Stephen H. Robinson, Maria Tsong


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