| Literature DB >> 12914768 |
Hiroshi Watanabe1, Meilei Ma, Takashi Washizuka, Satoru Komura, Tsuyoshi Yoshida, Yukio Hosaka, Katsuharu Hatada, Masaomi Chinushi, Tadashi Yamamoto, Kenichi Watanabe, Yoshifusa Aizawa.
Abstract
Atrial fibrillation is one of the common arrhythmias associated with hyperthyroidism. This study examined the effects of thyroid hormone (T3) on mRNA expression and currents of major ionic channels determining the action potential duration (APD) in the rat atrium using the RNase protection assay and the whole-cell patch-clamp technique, respectively. T3 increased the Kv1.5 mRNA expression and decreased the L-type calcium channel mRNA expression, while the Kv4.2 mRNA expression did not change. APD was shorter in hyperthyroid than in euthyroid myocytes. The ultrarapid delayed rectifier potassium currents were remarkably increased in hyperthyroid than in euthyroid myocytes, whereas the transient outward potassium currents were unchanged. L-type calcium currents were decreased in hyperthyroid than in euthyroid myocytes. T3 shifted the current-voltage relationship for calcium currents negatively. In conclusion, T3 increased the outward currents and decreased the inward currents. The resultant changes of ionic currents shortened APD, providing a substrate for atrial fibrillation.Entities:
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Year: 2003 PMID： 12914768 DOI： 10.1016/s0006-291x(03)01420-7
Source DB: PubMed Journal: Biochem Biophys Res Commun ISSN： 0006-291X Impact factor: 3.575