The synthesis of 0.01 millimole of diphenyl p-iodophenyl tetrazolium chloride from radioactive iodine (I131) is described. Following the intravenous injection of the radioactive tetrazolium salt into normal and tumor-bearing mice, radioactivity disappeared rapidly from the circulating blood, and appeared in greatest amount in kidney, liver, and lung. Sarcoma 37 contained less radioactivity than most other tissues.
This investigation was aided by a research grant from the National Cancer Institute, National Institutes of Health, U.S. Public Health Service.
Acknowledgment is due Mr. Myron Milden for technical assistance.