Using autologous platelets labelled in vitro with radioactive sodium Chromate duplicate platelet survival studies were carried out in six healthy asplenic men. At the first experiment plasma, and at the second a Ringer-citrate-dextrose (RCD) solution was employed as incubation medium.The uptake of Chromate by the platelets was about 2.5 times higher at the RCD- as compared to the plasma experiments. An identical pattern for the immediate behaviour of infused labelled platelets was observed at

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... e duplicate studies, and the recovery of platelet-bound radioactivity remained stable at the 90%-level during two post-infusional hours. At these experiments the means for platelet mean life span (MLS) were identical, 7.2±0.5 and 7.2±0.4 days, respectively. These values slightly, but not significantly, exceeded the mean platelet MLS for a control group consisting of ten young healthy males (6.9±0.4 days). The means for platelet production rate (P) at the duplicate studies made on the asplenic subjects were 19 ±2 × 1010 and 21 ±2 × 1010 platelets per day, respectively, and did not differ from the mean for P obtained in the control group (22 ±2 × 1010).