Abstract
Summary
A procedure is described for determination of the thyroid secretion rate in the intact rat. Based on inhibition of thyroidal I131 output by progressively increasing doses of thyroxine, it is applicable to individuals or small groups of animals. Values obtained by progressively increasing thyroxine dosage within individuals compare closely with those obtained by varying dosages between groups. They are also similar to reported values obtained by the goitrogen technic. Thyroid secretion values, expressed as μg L-thyroxine/100 g body weight were 2.21-2.56 for adult female and 2.15 for adult male rats. Rats given thiouracil to prevent further thyroidal combination of I131 during treatment yield values about 10% higher than those not receiving thiouracil.
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