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Further studies of the metabolism of thyroxine and 3,5,3′‐triiodothyronine in the guinea‐pig
Author(s) -
Brown-Grant K.
Publication year - 1967
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1967.sp008243
Subject(s) - triiodothyronine , endocrinology , guinea pig , medicine , hormone , urine , metabolism , thyroid , feces , chemistry , whole body counting , biology , paleontology , radionuclide , physics , quantum mechanics
1. Thyroxine labelled with 125 I and triiodothyronine labelled with 131 I have been administered simultaneously to guinea‐pigs and their metabolism studied by whole body counting and measurement of radioactivity in urine, faeces, and blood. 2. The half‐life of triiodothyronine in the body is about 19 hr, significantly less than that of thyroxine (41 hr). 3. After triiodothyronine administration, an unidentified iodinated compound appears in the blood which complicates the estimation of the half‐life of this hormone by measurement of the radioactivity in peripheral blood. 4. A previous report, based on measurements of blood radioactivity, that the half‐lives of the two hormones are similar in the guinea‐pig was not confirmed.