Thyroid hormone stimulates Na+-Ca2+ exchanger expression in rat cardiac myocytes

被引:18
作者
Hojo, Y
Ikeda, U
Tsuruya, Y
Ebata, H
Murata, M
Okada, K
Saito, T
Shimada, K
机构
[1] JICHI MED SCH, DEPT CARDIOL, MINAMI KAWACHI, TOCHIGI 32904, JAPAN
[2] JICHI MED SCH, DEPT ENDOCRINOL & METAB, MINAMI KAWACHI, TOCHIGI 32904, JAPAN
关键词
Na+-Ca2+ exchanger; thyroid hormone; sodium ion; cardiocyte; SODIUM-CALCIUM EXCHANGER; CHICK VENTRICULAR CELLS; SMOOTH-MUSCLE CELLS; SARCOPLASMIC-RETICULUM; GENE-EXPRESSION; HEART; HYPERTHYROIDISM; RECEPTOR; PROTEIN; ATPASE;
D O I
10.1097/00005344-199701000-00012
中图分类号
R5 [内科学];
学科分类号
1002 ; 100201 ;
摘要
We investigated whether thyroid hormone directly affects Na+-Ca2+ exchanger expression in cardiac myocytes. Cultured neonatal rat cardiocytes were prepared from 1-day-old Sprague-Dawley rats. Intracellular Na+ concentration ([Na+](i)) in cardiocytes was measured by using the Na+-sensitive dye sodium-binding benzofran isophthalate (SBFI). Na+-Ca2+ exchanger messenger RNA (mRNA) and protein expression were assayed by Northern and Western blotting, respectively Triiodothyronine (T-3; 10(-8) M) showed no effect on [Na+](i) in cardiocytes, whereas ouabain (100 mu M) caused a significant increase in [Na+](i) from 11.3+/-5.0 to 21.8+/-5.0 mM. Exposure of cardiocytes to ouabain caused a rapid increase in Na+-Ca2+ exchanger mRNA accumulation, with a maximal twofold elevation at 12 h. The ouabain-induced Na+-Ca2+ exchanger mRNA accumulation was still observed in the Ca2+-free culture medium. On the other hand, exposure of cardiocytes to T-3 induced a gradual increase in Na+ exchanger mRNA accumulation, with a maximal threefold increase at 24 h. Even in Na+-free medium, Tg still induced a twofold increase in Na+-Ca2+ exchanger mRNA accumulation in cardiocytes. Exposure of cardiocytes to T-3 for 24-48 h also caused a marked increase in Na+-Ca2+ exchanger protein accumulation. In conclusion, thyroid hormone directly increases cardiac Na+-Ca2+ exchanger expression, independent of alterations in Na+ mobilization. These findings suggest also that thyroid hormone and Na+ regulate Na+-Ca2+ exchanger gene expression through distinct molecular regulatory pathways.
引用
收藏
页码:75 / 80
页数:6
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