The Fate of P32 Labelled Diisopropylfluorophosphonate in the Human Body and Its Use as a Labelling Agent in the Study Of The Turnover of Blood Plasma and Red Cells

pound in the human organism became obvious. In the present study the absorption, the distribution in the blood and the excretion of DFP have been studied after intramuscular injection of the radioactive labelled substance (DFP32) into three patients suffering from myasthenia gravis (two cases) and arteriosclerosis cerebri, respectively, and into two normal persons. There are no theoretical reasons why the metabolic fate of DFP should be different from normal in the patients studied. Indeed, no essential differences were observed between results obtained from the three patients and those from the normal persons. Therefore, all results to be described should be considered as applicable to the metabolism of DFP in the normal human organism. In the course of this work it became obvious that the phosphorus of DFP32 was irreversibly bound to the proteins of blood plasma and red cells and that DFP was exclusively broken down to diisopropylphosphate, a substance which is not further metabolised nor taken up into any normal metabolic pool. Such properties suggested that DFP32 might prove to be a useful tool in the study of the turnover of blood plasma proteins and red cells. Preliminary results of the use of DFP32 in the determination of the life span of red cells and the half life of a plasma protein will be included in this study.