EFFECTS OF DIETARY IODINE ON THE UTILIZATION OF RADIOACTIVE IODINE BY THE RAT
Sprague-Dawley rats were fed on diets ranging from 40 mu g I/kg to 3885 mu g I/kg. Single doses of iodide-131 were injected intraperitoneally into each of the rats. In vivo measurements of radioisotope levels were made at intervals for 11 to 15 days over the neck and thorax. Thyroidal I/sup 131/ curves were obtained by using a fraction of the thoracic counts to correct for the extrathyroidal component of the neck counts. Animals on low-iodine diets concentrated I/sup 131/ in their thyroids more rapidly and to greater peak values, had lower protein-bound iodine (I/sup 127/) concentrations, and lower total thyroidal iodide (I/sup 127/) content than did rats in the high-iodine groups. An attempt was made to compensate the thyroidal counts for the continuing decrease in the concentration of iodide-131 in the plasma. From this attempt was derived the thyroidal index,'' a parameter which may be related to the rate of exchange of the total thyroidal iodine stores. Biological half-life values (I/sup 131/ in thyroid gland) for the low-iodine groups were larger than those for the high-iodine animals. The hypothesis is advanced that, at least for the conditions reported here, the biological half life does not adequately reflect thyroidal activity; exchange of iodine between the rat and its environment is considered to be the more important factor in controlling the numerical value of this parameter. (auth)
- Research Organization:
- Univ. of Western Ontario, London, Can.
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-17-030260
- OSTI ID:
- 4688393
- Journal Information:
- Can. J. Biochem. Physiol., Journal Name: Can. J. Biochem. Physiol. Vol. Vol: 41
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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