Excitation-contraction coupling in rat ventricular myocytes after formamide-induced detubulation
Excitation-contraction coupling in rat ventricular myocytes after formamide-induced detubulation
复制标题
DOI：
10.1152/ajpheart.1999.277.2.h603
复制
发表时间：
1999-08-01
影响因子：
4.8
通讯作者：
Orchard, CH
中科院分区：
文献类型：
--
作者：
Kawai, M;Hussain, M;Orchard, CH
甲酰胺诱导的渗透压休克已用于使分离的成年大鼠心室肌细胞去微管（即，破坏表面膜-T小管连接）。从细胞长度和宽度计算的细胞体积分别在应用和去除甲酰胺后迅速减少和增加。用甲酰胺处理后，膜电容降低了26.4%（从对照细胞的199.4 +/- 18.7 pF降低到甲酰胺处理细胞的146.7 +/- 6.4 pF; n = 1.3，P < 0.05）。而L型钙电流的幅度（Ic，）下降幅度更大（从0.75 ± 0.14到0.18 ± 0.03 nA; n = 5，P < 0.05），因此I-Ca密度下降了74.5%。同时测量I-Ca和Ca 2+瞬变（使用Fura 2监测）表明，去除甲酰胺后，两者均迅速下降。肌浆网Ca ~（2+）含量变化不大。交叉条纹，可视化与荧光染料二-8-aminonaphthylethenylpyridinium，稀疏或不存在的细胞，已用甲酰胺，这表明甲酰胺可以成功地去微管心脏细胞和I-Ca集中在T小管，因此发挥了重要作用，在兴奋收缩耦合。
Formamide-induced osmotic shock has been used to detubulate isolated adult rat ventricular myocytes (i.e., disrupt the surface membrane-T tubule junction). Cell volume, calculated from cell length and width, rapidly decreased and increased upon application and removal of formamide, respectively. After treatment with formamide, membrane capacitance decreased by 26.4% (from 199.4 +/- 18.7 pF in control cells to 146.7 +/- 6.4 pF in formamide-treated cells; n = 1.3, P < 0.05). However, the amplitude of the L-type Ca2+ current (Ic,) decreased by a greater extent (from 0.75 +/- 0.14 to 0.18 +/- 0.03 nA; n = 5, P < 0.05) so that the density of I-Ca decreased by 74.5%. Simultaneous measurements of I-Ca and Ca2+ transients (monitored using fura 2) showed that both decreased rapidly upon removal of formamide. However, the Ca2+ content of the sarcoplasmic reticulum showed little change. Cross-striations, visualized with the fluorescent dye di-8-aminonaphthylethenylpyridinium, were sparse or absent in cells that had been treated with formamide, suggesting that formamide can successfully detubulate cardiac cells and that I-Ca is concentrated in the T tubules, which therefore play an important role in excitation-contraction coupling.