Direct Measurement of Radioactive Sulfate Uptake by Rat Mast Cells. ∗

Summary

1) Radioactivity of S³⁵O₄ labeled cells can be measured directly with cells collected on Millipore filters. 2) Following a single intravenous injection of S³⁵O₄ rat peritoneal mast cells take up the radioactivity; the maximum is reached by 48 hours. No loss of radioactivity is evident in the following 5 days. Radioactivity in other free cells of peritoneal fluid attains a maximum at 4 hours and then falls rapidly to low levels.