Delayed changes of plasma level and biliary excretion of several iodothyronines after a single administration of low doses of thyroxine in rats.
Male Wistar rats were injected i.p. 2.5 or 5.0 micrograms thyroxine (T4) and the level of several iodothyronines and TSH in plasma or biliary excretion of iodothyronines were estimated by radioimmunoassay in groups of animals in various intervals up to 144 hr after the administration. In general, two peaks in the plasma level and biliary excretion of iodothyronines were found: first one within 24 hr and a delayed second one between about 48 and 72 hr after the administration. It was concluded that the first peak may correspond to the metabolic changes in fast tissue pools, while a second one might reflect some delayed iodothyronine metabolic steps in slow tissue pools after a bolus injection of T4.
Langer
P
P
Institute of Experimental Endocrinology, Slovak Academy of Sciences, Bratislava/Czechoslovakia.
Földes
O
O
Gschwendtová
K
K
D000818:Animals; D001646:Bile / Q000378:metabolism*; D004104:Diiodothyronines / Q000097:blood / Q000378:metabolism*; D008297:Male; D011863:Radioimmunoassay; D051381:Rats; D011919:Rats, Inbred Strains; D013970:Thyronines / Q000097:blood / Q000378:metabolism*; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000494:pharmacology*
D004104:Diiodothyronines; D013970:Thyronines; D013972:Thyrotropin; D013974:Thyroxine