PROLONGED INTRAVENOUS INFUSION OF LABELLED IODOCOMPOUNDS IN THE RAT: [125I]THYROXINE AND [125I]TRI-IODOTHYRONINE METABOLISM AND EXTRATHYROIDAL CONVERSION OF THYROXINE TO TRI-IODOTHYRONINE

1979 ◽  
Vol 82 (2) ◽  
pp. 235-241 ◽  
Author(s):  
VIPA BOONNAMSIRI ◽  
J. C. KERMODE ◽  
B. D. THOMPSON
Keyword(s):  
Steady State ◽  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Intravenous Infusion ◽  
Total Production ◽  
Continuous Intravenous Infusion ◽  
Faecal Excretion ◽  
Layer Chromatography

SUMMARY Extrathyroidal tissues of the rat were labelled to steady state by prolonged continuous intravenous infusion of 125I-labelled thyroxine (T4) or tri-iodothyronine (T3). Labelled iodocompounds extracted from various tissues were analysed by thin-layer chromatography. Significant amounts of labelled T3 were found in all tissues examined after infusion of [125I]T4, confirming that conversion of T4 to T3 occurs in extrathyroidal tissues of the rat. Faecal excretion of labelled T3 after [125I]T4 infusion provided an assessment of the extent of extrathyroidal conversion: about a third of the T4 was metabolized by this pathway. Extrathyroidal conversion was independently estimated to account for about a third of the total production of T3. The site of extrathyroidal conversion was established by comparing the distributions of labelled T3 after the two types of infusion: kidney and liver were both prominent sites of conversion of T4 to T3.

PROLONGED INTRAVENOUS INFUSION OF LABELLED IODOCOMPOUNDS IN THE RAT: [125I]IODIDE METABOLISM AND EFFECTS OF MODERATE DIETARY IODINE DEFICIENCY

1979 ◽  
Vol 82 (2) ◽  
pp. 227-234 ◽  
Author(s):  
VIPA BOONNAMSIRI ◽  
J. C. KERMODE ◽  
B. D. THOMPSON
Keyword(s):  
Skeletal Muscle ◽  
Iodine Deficiency ◽  
Intravenous Infusion ◽  
Structure And Function ◽  
Continuous Intravenous Infusion ◽  
Close Approximation ◽  
Faecal Excretion ◽  
And Function ◽  
Layer Chromatography ◽  
Secretion Rates

SUMMARY Radio-iodide was administered by prolonged continuous intravenous infusion to rats maintained under iodine-replete conditions and in moderate iodine deficiency. A close approximation to equilibrium labelling was thereby achieved. Labelled iodocompounds extracted from various tissues were analysed by thin-layer chromatography. Moderate iodine deficiency resulted in a slight increase in the ratio of mono-iodotyrosine to di-iodotyrosine in the thyroid. No change in the ratio of tri-iodothyronine (T3) to thyroxine (T4) was found in thyroid, plasma or skeletal muscle. Faecal excretion of T3 declined appreciably relative to that of T4. Under iodine-replete conditions the ratio of thyroidal secretion rates of T3 and T4 was estimated to be more than three times higher than the ratio of these iodocompounds within the thyroid. Heterogeneity of thyroglobulin structure and function may explain these observations.

Thin-Layer Chromatography

1965 ◽  
Author(s):  
H. R. Bolliger ◽  
M. Brenner ◽  
H. Gänshirt ◽  
Helmut K. Mangold ◽  
H. Seiler ◽  
...  
Keyword(s):  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Layer Chromatography

THE LESS-POLAR METABOLITES PRODUCED BY INCUBATION OF TESTOSTERONE-4-14C WITH RAT AND BOVINE BRAIN

1969 ◽  
Vol 61 (4) ◽  
pp. 641-648 ◽  
Author(s):  
Leon J. Sholiton ◽  
Emile E. Werk
Keyword(s):  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Paper Chromatography ◽  
Specific Activity ◽  
Bovine Brain ◽  
Polar Fraction ◽  
End Products ◽  
Polar Metabolites ◽  
Layer Chromatography ◽  
Constant Specific Activity

ABSTRACT Rat and bovine brain have been incubated with testosterone-4-14C under standard conditions. With use of paper chromatography, the extracted metabolites were noted to fall into less-polar, iso-polar, and more polar fractions. The components of the less-polar fraction were separated by acetylation and thin-layer chromatography and the major end-products identified by recrystallization to constant specific activity or constant 3H/14C ratios. Androst-4-enedione and 5α-dihydrotestosterone were formed consistently under the conditions utilized. Trace amounts of other less-polar metabolites were noted occasionally.

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