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Updated: Jul 28, 2026

An Ex vivo Culture System to Study Thyroid Development
Published on: June 6, 2014
Thyroid hormone export regulates cellular hormone content and response
R C Ribeiro1, R R Cavalieri, N Lomri
1Department of Medicine, University of California, San Francisco, California 94143-0540, USA.
Abstract:
Actions of thyroid hormones (THs) are determined by intracellular free hormone concentration. Here we report that enhanced TH extrusion via a saturable, cold-sensitive mechanism lowers intracellular TH and causes TH resistance in hepatoma cells. Since these cells overexpress multidrug resistance P-glycoproteins and TH extrusion and resistance are blunted by verapamil, P-glycoproteins may mediate this resistance. Verapamil-inhibitable TH efflux was also found in primary hepatocytes, cardiocytes, and fibroblasts. These findings demonstrate that TH extrusion can modulate TH availability and action in mammalian cells.
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