Thyroid hormone-binding proteins in plasma facilitate uniform distribution of thyroxine within tissues: a perfused rat liver study.

Abstract:

:We used autoradiography to test the hypothesis that a major function of thyroid hormone-binding proteins in plasma is to ensure uniform distribution of thyroid hormones among cells of a given tissue. The distribution of [125I]T4 within rat hepatic lobules was determined after its single pass perfusion through the portal vein in solutions containing or lacking thyroid hormone-binding proteins. These proteins included thyroid hormone-binding globulin, thyroid hormone-binding prealbumin, and albumin. In the absence of these proteins, virtually all of the perfused T4 was taken up by the periportal cells, and subsequent perfusion with protein-free solution did not cause redistribution of this T4. In the presence of these proteins, in contrast, the perfused T4 was taken up uniformly by all cells within the lobule. Albumin alone was sufficient to ensure uniform cellular uptake of T4. However, variation of oleic acid concentrations within the physiological range markedly influenced the concentration of free T4 in a solution of 4% human serum albumin, but not in human serum. These results indicate that uniform distribution of T4 within tissues requires circulating thyroid hormone-binding proteins, and that the specific binding proteins, thyroid hormone-binding globulin and thyroid hormone-binding prealbumin, are required to ensure nonfluctuating circulating concentrations of free T4 in vivo. Other hormone-binding proteins in plasma and some transport proteins may function similarly.

journal_name

Endocrinology

journal_title

Endocrinology

authors

Mendel CM,Weisiger RA,Jones AL,Cavalieri RR

doi

10.1210/endo-120-5-1742

subject

Has Abstract

pub_date

1987-05-01 00:00:00

pages

1742-9

issue

5

eissn

0013-7227

issn

1945-7170

journal_volume

120

pub_type

杂志文章