IRON 203 



cooled, and the fat skimmed off. The sohition was made up to 200 ml 

 with washings from the beaker and fat. Fifty-milliiiter ali(]Uots were 

 dry-ashed and electroplated following the methods described above 

 (Fe-6). 



In a double-labeling experiment with rats (Fe-9), Fe^^ containing 

 125,000 counts/min and 8 ^g iron was given orally, whereas 10.000 

 counts/min of Fe^^ in 0.1 /xg iron was incubated for 1 hr with 1 ml of rat 

 plasma and injected intravenously. Blood and tissues were wet-ashed 

 with sulfuric and perchloric acids, whereas the carcass was dry-ashed. 

 The iron was electroplated for the counting of Fe^^ with an argon-filled 

 Geiger tube plus a beryllium filter, and for the counting of Fe^'-* with a 

 helium-filled tube. Doses of 200,000 to 1,000,000 counts/min of Fe^" 

 containing 1.8 to 120 mg iron were administered orally to women patients 

 (Fe-10). The red cells were dry-ashed at G20°C, and the ash solutions 

 electroplated by the methods described in (Fe-3). 



For histochemical studies, guinea pigs, rats, and a dog were given about 

 88, 4.4, and 380 /xc, respectively, of Fe^^''^^ orally (Fe-U). Tissues were 

 fixed in Carnoy's fluid and Formalin or alcohol-Formalin and were stained 

 for iron by Dry's modification of Perl's method or by Gomori's method. 

 A paraffin section stained by Dry's method was used for a routine contact 

 autoradiogram with Ansco nonscreen X-ray film. After exposure, the 

 preparation was developed, fixed, dried, mounted in xylol-Clarite, and 

 covered with a cover slip. 



Labeled rat hemoglobin was prepared by use of a ferrous chloride- 

 lactic acid solution in doses of 0.25 ml/ 100 g body weight containing 1 mg 

 iron and 3300 counts/min (Fe-12). The optimum solution contained 

 400 mg % iron in 0.1 N lactic acid and was sterilized by filtration for 

 storage. The rats were bled about 1.5 per cent of their body weight at 

 2- to 3-day intervals for 11 bleedings, and the injections were then begun 

 daih^ for 7 days and then every other day for another seven doses. In 

 another study, labeled cytochrome C was produced by administration of 

 about 11 mg of high-specific-activity Fe^^-labeled iron to iron-depleted 

 young rats (Fe-13). The cytochrome C was isolated to contain about 

 1235 counts/min/mg. 



To study the effect of manganese on iron uptake, peanut plants were 

 grown in nutrient solution containing var3dng amounts of manganese to 

 which labeled iron was added. Each quart fruit jar, which contained the 

 roots of two plants, received 14 /zc Fe^^ (Fe-14). Leaflets, which were 

 taken 24 to 120 hr after addition of the Fe^', were pressed between blot- 

 ting paper, dried for 48 hr at 105°C, weighed, and then counted in an 

 internal proportional counter. It was shown that the counts were essen- 

 tially the same whether the leaflets were counted directly or digested in 

 HNOs, dried, and counted: the results were generally reproducible. 



