Endocrinology, Vol 114, 992-997, Copyright © 1984 by Endocrine Society

ARTICLES

Effect of hypothyroidism and hyperthyroidism on triiodothyronine production in perfused rat liver

AS Jennings, FL Crutchfield and MB Dratman

This study was undertaken to evaluate the effect of altered thyroid states on hepatic T3 production in a functioning intact organ system, the isolated perfused liver. Thyroidectomized rats were treated for 3-4 weeks with vehicle, T4, 1.5 micrograms/100 g-1 day-1, or T4, 20 micrograms/100 g-1 day-1, to produce hypothyroidism, euthyroidism, or hyperthyroidism. Livers were perfused for 1 h with medium containing T4, 10 micrograms/dl, and T3 production was estimated by RIA. T3 production in the hypothyroid, euthyroid, and hyperthyroid groups, respectively, was 1.61 +/- (SE) 0.50, 5.18 +/- 0.55, and 15.62 +/- 1.61 ng/g-1 liver h-1. These differences in T3 production resulted entirely from changes in percent conversion of T4 to T3 which were 0.87 +/- 0.25%, 3.21 +/- 0.38%, and 12.02 +/- 1.82% in the hypothyroid, euthyroid, and hyperthyroid groups, respectively. The measured hepatic uptake of T4 decreased slightly with T4 administration from 188 +/- 13 to 162 +/- 7 and 144 +/- 10 ng/g liver in these same groups. The changes in T3 production were not accounted for by differences in biliary excretion or deiodination of T3. These studies demonstrate a stimulatory effect of T4 on the conversion of T4 to T3 which is important to altering net hepatic T3 production.

This article has been cited by other articles:

				L. A. Burmeister, J. Pachucki, and D. L. St. Germain Thyroid Hormones Inhibit Type 2 Iodothyronine Deiodinase in the Rat Cerebral Cortex by Both Pre- and Posttranslational Mechanisms Endocrinology, December 1, 1997; 138(12): 5231 - 5237. [Abstract] [Full Text] [PDF]