help button home button Endocrine Society Endocrinology
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
This Article
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow Request Copyright Permission
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Murthy, P. V.
Right arrow Articles by McKenzie, J. M.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Murthy, P. V.
Right arrow Articles by McKenzie, J. M.

Endocrinology, Vol 102, 1129-1136, Copyright © 1978 by Endocrine Society

ARTICLES

Hypothyroidism-induced changes in triiodothyronine binding to nuclei and cytosol-binding proteins in rat liver

PV Murthy, K Banovac and JM McKenzie

A tracer dose of [125I]T3 was given iv to normal, thyroidectomized, and propylthiouracil-fed rats and the distribution of radioactivity in serum and liver fractions was studied over 1 h. Total liver homogenate and serum 125I were higher at all times in hypothyroid rats and, in all groups, showed a continuous fall over the period studied. Hepatic nuclear 125I was maximal at 20 min in all and was greater in hypothyroid rats; there was more 125I in the hepatic cytosol of normal rats than in that from either thyroidectomized or propylthiouracil-fed animals. Binding studies with [125I]T3 and purified hepatic neclear preparations in vitro indicated that both the association constant, Ka (1.08-9.0 x 10(9) M-1) and the capacity (500-600 pg/mg DNA) in thyroidectomized and goitrogen-treated rats were similar to those obtained with normal animals. Cytosol, on the other hand, showed a decrease in binding capacity without change in affinity in livers of hypothyroid rats. Analysis of binding data by Hill plots indicated the presence of both positive and negative cooperativity in binding of T3 by rat liver cytosol proteins. In the in vitro experiments, higher serum radioactivity alone could not account for increases in the hepatic nuclear 125I in the hypothyroid rats because cytosol 125I (presumably in dynamic exchange with both blood and nuclei) was less. Consequently, cytosol T3-binding proteins may regulate the free T3 concentration in the cell and, thus influence the distribution of the hormone in other cellular compartments.


This article has been cited by other articles:


Home page
 ScienceHome page
M. Dratman, Y Futaesaku, F. Crutchfield, N Berman, B Payne, M Sar, and W. Stumpf
Iodine-125-labeled triiodothyronine in rat brain: evidence for localization in discrete neural systems
Science, January 15, 1982; 215(4530): 309 - 312.
[Abstract] [PDF]


HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Endocrinology Endocrine Reviews J. Clin. End. & Metab.
Molecular Endocrinology Recent Prog. Horm. Res. All Endocrine Journals
Copyright © 1978 by The Endocrine Society