Excessive thyroxine enhances susceptibility to apoptosis and decreases contractility of cardiomyocytes
| Autor: | Bo Jiao, Wang-Gang Guo, Hong-Lei Che, Yun-Ying Wang, Zhi-Bin Yu |
|---|---|
| Rok vydání: | 2010 |
| Předmět: |
Male
medicine.medical_specialty Surface Properties Levothyroxine Apoptosis Cell Separation DNA Fragmentation In Vitro Techniques DNA laddering Hyperthyroidism Biochemistry Muscle hypertrophy Rats Sprague-Dawley Contractility Necrosis Endocrinology Heart Rate Internal medicine In Situ Nick-End Labeling medicine Animals Myocyte Myocytes Cardiac Molecular Biology Cells Cultured Cell Size business.industry Myocardium Stroke Volume Organ Size Stroke volume medicine.disease Myocardial Contraction Angiotensin II Rats Thyroxine Heart failure business medicine.drug |
| Zdroj: | Molecular and Cellular Endocrinology. 320:67-75 |
| ISSN: | 0303-7207 |
| DOI: | 10.1016/j.mce.2010.01.031 |
| Popis: | Excessive thyroid hormone induces cardiac hypertrophy and promotes heart failure in patients with hyperthyroidism, but the mechanism remains elusive. Rats were orally administered with levothyroxine (100 microg/kg, T(4)) for 4 weeks to induce hyperthyroidism. The calculated stroke volume decreased and the shortening amplitude-frequency relationship in unloaded contraction of isolated cardiomyocytes was negative in T(4)-treated rats. Apoptotic rates increased and DNA laddering was also detectable in T(4)-treated rat hearts. By contrast, in primary cultured cardiomyocytes, T(3) induced dose-dependent hypertrophy but did not affect the apoptotic rate. Angiotensin II further increased the apoptotic rate of T(3)-induced hypertrophied cardiomyocytes. The apoptotic rate was dependent on the extent of cardiomyocyte hypertrophy. These results suggest that cardiac contractility is enhanced during the early stage of hyperthyroidism, but decreased during the late stage of hyperthyroidism. The hypertrophied cardiomyocytes were also susceptible to apoptotic stimulation by angiotensin II. Depressed cardiac contractility and enhanced apoptosis may lead to heart failure in hypertrophied myocardium. |
| Databáze: | OpenAIRE |
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