The Mechanism of the Action of Iodides on the Nitrogen Metabolism.

It has been shown by a number of observers that the administration of iodides both to dogs and to human beings causes an increase in the output of nitrogen in the urine. One of the earliest observers (1) working with dogs showed that this was in part at the expense of the nitrogen excreted in the feces, but that the total amount of nitrogen excreted was none the less increased. We have been able to confirm this in human beings and also in the dog. Iodine has been shown to have lytic effects on fibrous tissue of which this increased nitrogen elimination may be a manifestation. Soilman (2) too has demonstrated this lytic action on subcutaneous nodules produced by the injection of local anesthetics. Various hypotheses have been offered to explain the mechanism of this action of iodides. Tnhibition of antitryptic activity of the blood has been postulated by Jobling and Peterson (3) to account for the lytic action of iodine. In previous work from this laboratory it has been shown that in the human being there is an increase in the nitrogen excretion following the ingestion of iodides (4). It has been further shown that this increase does not change the nitrogen partition (5). It has been shown that the administration of sodium iodide for three days is accompanied by an immediate increase of 15 per cent in the nitrogen excretion in the urine, coinciding with the period of drug administration. During this period the non-protein nitrogen of the blood fell only slightly. However, when potassium iodide was administered the increased excretion of nitrogen was delayed and the non-protein nitrogen of the blood rose until the increased excretion began. Consequently this nitrogen must come from some source in the body rather than represent simple retention due to kidney impermeability