瞬时受体电位亚族M7在小鼠心肌梗死后的表达变化及其意义

Increased expression of transient receptor potential melastatin 7 in mouse cardiac fibroblasts post myocardial infarction

目的观察小鼠心肌梗死后成纤维细胞（CF）上瞬时受体电位亚族M7样电流（TRPM7L）的变化及其对Ca^2＋信号的影响，探讨瞬时受体电位亚族（TRP）M7离子通道在CF功能中的作用。方法制备小鼠心肌梗死模型并分离小鼠CF，培养传代小鼠CF及其基因沉默技术（SiRNA）转染，应用膜片钳技术观察小鼠CF缺血后及低pH值溶液下TRPM7L内外向电流特征，用钙荧光显像技术观察缺血心肌、酸性pH值时小鼠CF的Ca^2＋内流变化，测定缺血时小鼠CF细胞总胶原含量改变。结果（1）小鼠CF上富含TRPM7表达，且TRPM7L电生理特性与TRPM7通道一致；（2）心肌缺血使小鼠CF的Ca^2＋内流较对照组增加[（7．4±0．7）pA／pF比（16．2±1．7）pA／pF，P〈0．01]，而酸中毒时增加3倍；（3）SiRNA显著减少TRPM7L的mRNA丰度和90％的电流幅值。结论TRPM7是小鼠CF细胞中TRPM7L的分子基础；TRPM7L是CF中钙内流主要媒介；致纤维化因素（缺血、酸中毒等）通过调节TRPM7L介导的Ca^2＋信号机制影响小鼠CF细胞的病理生理功能，在心肌纤维化的形成中可能发挥重要作用。

Objective To observe transient receptor potential melastatin 7-like （TRPM7L） expression changes post myocardial infarction （MI） in mouse cardiac fibroblast （CF）. Methods TRPM7 expression and Ca^2＋ influx in CF from MI and control mice were quantified by mRNA RT-PCR and whole cell patch clamp technique. Results （ 1 ） TRPM7 expression was significantly upregulated post MI and Ca2~ influx of CF were significantly increased post MI [ （7.4 ±0.7）pA/pF vs. （ 16.2 ± 1.7）pA/pF, P 〈 0.01 ] and Ca^2＋ influx of CF increased 3-fold under lower pH condition; （2） These effects could be blocked by knock-out TRPM7 gene with SiRNA. Conclusion TRPM7L upregulation post MI and under lower pH condition are responsible for increased Ca^2± influx in CF.