EFFECTS OBSERVED IN THE WHOLE ANIMAL 245 



dental caries (Table 1-38). Since iodoacetate-P^^ may release some inor- 

 ganic I^^^ into the tissues, a comparable study was made using iodide-P^^. 

 The maximal uptake occurred around 3 hr and the analyses were done at 

 this time. Iodide is picked up selectively only by the thyroid and the con- 

 centrations in the other tissues are low. lodoacetate concentrations are 



Table 1-38 

 Distribution of Iodoacetate-I'^^ and Iodide-I"i in Rat Tissues" 



" lodoacetate injected intraperitoneally at a dose of 50 mg/kg in rats and tissues 

 analyzed at 3 hr. The figures give the per cent of the administered dose of labeled 

 substance per gram fresh weight of tissue. (From Thomassen and Leicester, 1951.) 



about twice those of iodide in most tissues. The high thyroid level after 

 administration of iodoacetate is probably due to the release of a small 

 amount of labeled iodide, which is avidly accumulated. This may also ex- 

 plain the somewhat greater concentration in saliva. There is no evidence 

 for appreciable selective uptake of iodoacetate by any tissue. It is interest- 

 ing that skeletal muscle has a relatively low concentration of iodoacetate, 

 which might be anticipated on the basis of the general anionic impermeabil- 

 ity of muscle. It is unfortunate that the brain was not analyzed, but it is 

 likely that the iodoacetate level would have been quite low. The retention 

 in the tissues seems to be rather long, but it is not known if this represents 

 iodoacetate or iodide. 



When iodoacetamide-I^^^ is injected intraperitoneally into mice, the blood 

 level rises rather rapidly and falls rapidly during the first hour, being essen- 

 tially gone by 7 hr (Friedman and Rutenberg, 1950 b). The initial rapid fall 



