Effect of Phosphate Loading on Leukocyte Labelling with Inorganic P 32 . ∗

Summary

The effect of an intravenous load of non-isotopic inorganic phosphate following P³² on plasma clearance and on leukocyte labelling has been studied. Such a load produces immediate dilution of plasma phosphate activity, decreases rate of clearance of plasma radioactivity during the period of loading, diminishes the level of labelling of circulating leukocyte acid soluble and DNA phosphorus, and prevents development of a peak in DNA-P specific activity. The findings suggest that marrow labelling during the first 2 hours after P³² injection is responsible for development of the peak in DNA-P specific activity found in peripheral blood leukocytes.