122 



Scientific Proceedings (29). 



75 (33i) 



On the pharmacology of the iodides. 



By L. B. STOOKEY and VERA GARDNER. 



[From the Physiological Laboratory, Medical School, University of 

 Southern California.] 



In an earlier paper it was suggested by one of us that the 

 internal secretion of the thyroids may influence metabolism in the 

 manner of a kinase, namely, by activating some intracellular oxi- 

 dases. 



In view of a close parallelism existing between the iodine 

 content of the thyroids and the physiological action of thyroid 

 preparation it seemed possible that the administration of iodides 

 might lead to an increased power to effect certain oxidative 

 changes. 



To test this hypothesis, the capacity of tissue taken from normal 

 dogs to oxidize indol was compared with that of tissues taken 

 from dogs treated with potassium iodide (o. 1 gram per kilo daily) 

 over variable periods. The dogs were bled from the carotids, the 

 organs removed under the usual precautions, hashed, divided into 

 convenient quantities and exposed to seven times their weight of 

 0.005 P er cent, indol solution. Toluol was added to prevent 

 bacterial action. The mixtures were kept at body temperature, 

 and the amount of unoxidized indol was determined at varying 

 intervals. The indol was estimated colorimetrically by means of 

 the glyoxylic acid reaction. Results obtained in this manner 

 were checked by Kjeldahl nitrogen determinations. 



In all cases the administration of potassium iodide in the dog 

 was found to lead to an increased power on the part of the liver, 

 kidneys and spleen to oxidize indol. 



While the influence of iodides upon intracellular oxidation 

 might appear to be exerted through the thyroids, it is possible that 

 a direct action without the intervention of the thyroids may take 

 place. In this connection it is scarcely necessary to remark that 

 the striking similarity between the action of iodides and that of 

 thyreoglobulin was recognized long ago. Many symptoms of 

 iodism are very similar to those of thyroidism, namely, tachycardia, 



