Thyroid Hormone-Induced Alterations of Ryanodine and Dihydropyridine Receptor Protein Expression in Rat Heart
Thyroid Hormone-Induced Alterations of Ryanodine and Dihydropyridine Receptor Protein Expression in Rat Heart
- Hae Won Kim Miyoung Park Eun Hee Lee Hyoung Jin Cho Hee Ran Lee
- 대한생리학회-대한약리학회
- The Korean Journal of Physiology & Pharmacology
- 제3권 제3호
- 등재여부 : KCI등재
- 1999.01
- 329 - 337 (9 pages)
<P> Thyroid hormone-induced cellular dysfunctions may be associated with changes in the intracellular Ca<SUP>2⁢</SUP> concentration. The ryanodine receptor, a Ca<SUP>2⁢</SUP> release channel of the SR, is responsible for the rapid release of Ca<SUP>2⁢</SUP> that activates cardiac muscle contraction. In the excitation-contaction coupling cascade, activation of ryanodine receptors is initiated by the activity of sarcolemmal Ca<SUP>2⁢</SUP> channels, the dihydropyridine receptors. In hyperthyroidism left ventricular contractility and relaxation velocity were increased, whereas these parameters were decreased in hypothyroidism. The mechanisms for these changes have been suggested to include alterations in the expression and/or activity levels of various proteins. In the present study, quantitative changes of ryanodine receptors and the dihydropyridine receptors, and the functional consequences of these changes in various thyroid states were investigated. In hyperthyroid hearts, [<SUP>3</SUP>H]ryanodine binding and ryanodine receptor mRNA levels were increased, but protein levels of ryanodine were not changed significantly. However, the above parameters were markedly decreased in hypothyroid hearts. In case of dihydropyridine receptor, there were a significant increase in the mRNA and protein levels, and [<SUP>3</SUP>H]nitrendipine binding, whereas no changes were observed in these parameters of hypothyroid hearts. Our findings indicate that hyperthyroidism is associated with increases in ryanodine receptor and dihydropyridine receptor expression levels, which is well correlated with the ryanodine and dihydropyridine binding. Whereas opposite changes occur in ryanodine receptor of the hypothyroid hearts.