Ohkubo Tsuyako, Kawarabayashi Tatsuhiko, Inoue Yoshihito, Kitamura Kenji
Department of Physiological Science & Molecular Biology, Fukuoka Dental College Fukuoka, Japan.
Gynecol Obstet Invest. 2005;59(2):80-5. doi: 10.1159/000082333. Epub 2004 Nov 25.
The aim of this study was to evaluate the difference in the expression of mRNA of two types of calcium channels between longitudinal and circular muscle layer of rat myometrium during pregnancy. Changes in the expressions of the mRNA encoding L-type (alpha1C) and T-type (alpha1G, alpha1H, and alpha1I) calcium channels in longitudinal and circular smooth muscle cells of the rat myometrium were examined using a comparative kinetic RT/PCR method. During the course of pregnancy, alpha1C mRNA expression showed an N-shaped change in longitudinal muscle, but simply increased after mid-pregnancy in circular muscles. The mRNAs for alpha1G and alpha1H, but not that for alpha1I, were expressed in both longitudinal and circular smooth muscle. In longitudinal muscle, the change in alpha1H mRNA was similar to that in alpha1C mRNA during gestation, but the expression of alpha1G mRNA changed significantly only at term (day 22). In circular muscle, alpha1H mRNA expression was stable at any stage during pregnancy, but alpha1G mRNA significantly increased on day 15 and at term. No relationship was observed between voltage-dependent calcium-channel mRNA expressions and either proliferation or hypertrophy of circular muscle during pregnancy. These results show (a) that during pregnancy, the expression levels of L-type channels change dynamically, and it may contribute directly to the regulation of cell excitability, and (b) that the T-subtype that increases during pregnancy differs between longitudinal and circular muscle cells, although their functions remain unclear.
本研究旨在评估孕期大鼠子宫肌层纵行肌层和环行肌层中两种钙通道mRNA表达的差异。采用比较动力学RT/PCR方法检测大鼠子宫肌层纵行和环行平滑肌细胞中编码L型（α1C）和T型（α1G、α1H和α1I）钙通道的mRNA表达变化。在孕期过程中，α1C mRNA表达在纵行肌中呈N形变化，但在环行肌中孕中期后仅简单增加。α1G和α1H的mRNA在纵行和环行平滑肌中均有表达，但α1I的mRNA没有。在纵行肌中，α1H mRNA的变化在妊娠期间与α1C mRNA相似，但α1G mRNA的表达仅在足月时（第22天）有显著变化。在环行肌中，α1H mRNA表达在孕期的任何阶段都稳定，但α1G mRNA在第15天和足月时显著增加。在孕期，未观察到电压依赖性钙通道mRNA表达与环行肌增殖或肥大之间的关系。这些结果表明：（a）孕期L型通道的表达水平动态变化，可能直接参与细胞兴奋性的调节；（b）孕期增加的T亚型在纵行和环行肌细胞中不同，尽管其功能尚不清楚。
