Distribution of C 14 -Labeled Alloxan in the Tissues of the Rat and its Mode of Elimination. ∗

Summary

1. Two alloxan preparations, labeled in the 2- and in the 5-position with C¹⁴, were administered subcutaneously to rats. Both labeled compounds were rapidly excreted in the urine, to the extent of 90-95% in 22 hours. Negligible proportions of the C¹⁴ were found in urea. 2. With either tracer or diabetogenic doses, the radioactivity was highest in the kidneys and plasma, and reached a peak at approximately 15 minutes. The other tissues studied, including pancreas, had much lower C¹⁴ concentrations. 3. With either alloxan-2 or 5-C¹⁴, very little radioactivity appeared as C¹⁴O₂ in expired air. 4. It is concluded that the alloxan molecule does not undergo extensive catabolism in the rat.