Overall mean concentration of total radioactivity associated with plasma or blood cells following IV administration of ¹²⁵I-rmTPO. Mice received a single IV bolus injection of ¹²⁵I-rmTPO or ¹²⁵I-rmTPO + 10 μg rmTPO and were sacrificed 3 hours later. Citrated blood was collected and the amount of radioactivity per milliliter of blood determined. The blood was washed, centrifuged and the radioactivity associated with the blood cells determined. The remaining radioactivity was associated with plasma. The data were expressed as cpm/mL of blood. Black bars represent ¹²⁵I-rmTPO and gray bars represent ¹²⁵I-rmTPO + 10 μg rmTPO. *Indicates values are significantly different (P < .05).