Document Detail

Short-term effects of thyroid hormones and 3,5-diiodothyronine on membrane transport systems in chick embryo hepatocytes.
MedLine Citation:
PMID:  11956147     Owner:  NLM     Status:  MEDLINE    
Rapid nongenomic effects of thyroid hormones L-T(3) and L-T(4) on two plasma membrane transport systems were investigated in 14-d-old and 19-d-old chick embryo hepatocytes. The Na(+)/H(+) exchanger activity was measured using the intracellular pH-sensitive fluorescent probe 2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein acetoxymethyl ester, whereas the amino acid transport was estimated by [1-(14)C]-2-aminoisobutyric acid uptake. System A amino acid transport activation was linear to hormone concentration, whereas the Na/H exchanger gave a bell-shaped dose-response curve, with a maximum at the physiological hormone concentration of 1 nM. The specificity of the effect was verified by the use of inhibitors and analogues. The thyroid hormone analog 3,5-diiodo-L-thyronine was able to mimic some of the hormone effects, but with a lower efficiency. The effect on the Na(+)/H(+) exchanger was identified for 14-d-old and 19-d-old cells, whereas the amino acid transport could only be activated at the late stage of embryo development. Both transport systems were activated through a signal transduction pathway involving PKC, MAPK pathway, and PI3K, even though the differences in response behavior indicate a differential modulation of the two transport systems by L-T(3) and L-T(4). These results clearly demonstrate the existence of rapid nongenomic action of thyroid hormones also in avian cells, and show that activation of System A amino acid transport is not directly correlated to changes in intracellular pH. For the first time, evidence is presented which suggests that short-term effects of thyroid hormones may play a role during fetal development and cell differentiation.
Sandra Incerpi; Paolo De Vito; Paolo Luly; Silvana Spagnuolo; Silvia Leoni
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Endocrinology     Volume:  143     ISSN:  0013-7227     ISO Abbreviation:  Endocrinology     Publication Date:  2002 May 
Date Detail:
Created Date:  2002-04-16     Completed Date:  2002-05-09     Revised Date:  2009-11-19    
Medline Journal Info:
Nlm Unique ID:  0375040     Medline TA:  Endocrinology     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1660-8     Citation Subset:  AIM; IM    
Department of Biology, University of Rome Roma Tre, Viale Marconi 446, 00146 Rome, Italy.
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MeSH Terms
1-Phosphatidylinositol 3-Kinase / antagonists & inhibitors,  metabolism
Amino Acids / metabolism
Biological Transport, Active / drug effects
Cell Membrane / drug effects,  metabolism
Chick Embryo
Diiodothyronines / pharmacology*
Enzyme Inhibitors / pharmacology
Hepatocytes / drug effects,  metabolism*
Hydrogen-Ion Concentration
Mitogen-Activated Protein Kinases / antagonists & inhibitors,  metabolism
Protein Kinase C / antagonists & inhibitors,  metabolism
Signal Transduction / drug effects
Sodium-Hydrogen Antiporter / metabolism
Thyroid Hormones / pharmacology*
Reg. No./Substance:
0/Amino Acids; 0/Diiodothyronines; 0/Enzyme Inhibitors; 0/Sodium-Hydrogen Antiporter; 0/Thyroid Hormones; 534-51-0/3,5-diiodothyronine; EC 3-Kinase; EC Kinase C; EC Protein Kinases

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