132 



Scientific Proceedings (66). 



79 (ion) 



Demonstration in vitro of the specific affinity of thyroid cells for 



iodin. 



By David Marine. 



[From the H. K. disking Laboratory of Experimental Medicine, 

 Western Reserve University, develand.] 



It is a well-known fact that thyroid tissue in vivo has a specific 

 affinity for iodin. This has been demonstrated in several ways. 

 The simplest and most obvious means is afforded by taking 

 advantage of the spontaneous active hyperplasia of dogs. Having 

 shown that the per cent, of iodin in the gland varies inversely 

 with the degree of active hyperplasia, we were able to demonstrate 

 that the ability of the gland to take up iodin varies with the 

 degree of active hyperplasia present; or if expressed from the 

 viewpoint of chemistry, the ability of thyroid tissue in vivo to 

 take up iodin varies inversely with the degree of saturation of the 

 gland with iodin. Such relatively large proportions of a given 

 intake of iodin may be stored by the thyroid (for example, the 

 recovery of 4.5 mgm. I from a 7.2 gram thyroid lobe in a dog 

 weighing 8 kilos from a total of 50 mgm. KI given by mouth in 



10 days) in vivo that it seems likely the surviving thyroid cells 

 in vitro would exhibit this same affinity, and if so it could readily 

 be demonstrated by perfusion. 



We have perfused a large series of spleens, kidneys and thyroids 

 of dogs, using defibrinated blood containing ]^ (by volume) of 

 Ringer's solution. Iodin as KI was added to the perfusion fluid 

 in amounts varying from 5 mgm. to 40 mgm. All perfusions were 

 carried out at temperatures varying between 35 0 and 37 0 C. All 

 the thyroid lobes used were goitrous, varying histologically from 

 marked active hyperplasias to colloid goitres, and in weight from 



11 to 81 grams. The perfusions were continued from 1 to 2 hours, 

 and the glands washed with Ringer's for 20 minutes. Iodin and 

 histological examinations were made both on the control and the 

 perfused glands. It was found that relatively large amounts of 

 the KI were held in the thyroid which could not be washed out 



