Endocrinology, Vol 117, 1639-1644, Copyright © 1985 by Endocrine Society

ARTICLES

Multisite inhibition by ipodate of iodothyronine secretion from perfused dog thyroid lobes

P Laurberg

Cholecystographic radiocontrast agents interfere with thyroid hormones in several ways. In the present study 1 mM ipodate induced a rapid sustained and reversible inhibition of the secretion of T4, T3, rT3, 3,3'-diiodothyronine, and 3',5'-diiodothyronine from perfused dog thyroid lobes. This effect was not reproduced by infusion of 3 mM iodide and not affected by 2 mM methimazol or 2 mM perchlorate. One millimolar of ipodate inhibited secretion of T4 to 23.7 +/- 2.8% of control (+/- SE, n = 6), 0.3 mM ipodate to 59.6 +/- 3.01 (n = 4), and 0.1 mM ipodate to 80.4 +/- 5.7% of control (n = 4). In search of the site of action in the thyroid of this inhibitory compound it was found that 1 mM ipodate inhibited TSH-induced increase in thyroidal cAMP, cAMP-induced generation of intracellular colloid droplets, and liberation of T4 and T3 from thyroglobulin by acid proteases and peptidases. These processes are those thought to be inhibited during iodide inhibition of thyroid secretion, via gradual formation of an unknown iodine-containing organic intermediate. It is suggested that the inhibition of thyroid secretion observed in the present study is due to structural similarities between ipodate and this putative iodine- containing mediator of the iodide-induced inhibition of thyroid secretion.

This article has been cited by other articles:

				C. S. Bal, A. Kumar, and P. Chandra Effect of Iopanoic Acid on Radioiodine Therapy of Hyperthyroidism: Long-Term Outcome of a Randomized Controlled Trial J. Clin. Endocrinol. Metab., December 1, 2005; 90(12): 6536 - 6540. [Abstract] [Full Text] [PDF]

				F. Bogazzi, L. Bartalena, C. Cosci, S. Brogioni, E. Dell'Unto, L. Grasso, F. Aghini-Lombardi, G. Rossi, A. Pinchera, L. E. Braverman, et al. Treatment of Type II Amiodarone-Induced Thyrotoxicosis by Either Iopanoic Acid or Glucocorticoids: A Prospective, Randomized Study J. Clin. Endocrinol. Metab., May 1, 2003; 88(5): 1999 - 2002. [Abstract] [Full Text] [PDF]

				I. J. Chopra and K. Baber Use of Oral Cholecystographic Agents in the Treatment of Amiodarone-Induced Hyperthyroidism J. Clin. Endocrinol. Metab., October 1, 2001; 86(10): 4707 - 4710. [Abstract] [Full Text] [PDF]

				M. Braga and D. S. Cooper Oral Cholecystographic Agents and the Thyroid J. Clin. Endocrinol. Metab., May 1, 2001; 86(5): 1853 - 1860. [Abstract] [Full Text]