Roles of Voltage- and cation-independent TRPC channels in cardiac hypertrophy

我们报道了血管紧张素II或内皮素-1刺激通过瞬时受体电位规范通道3 （TRPC3）和trpc6介导的Ca2+内流在大鼠新生心肌细胞中诱导肥厚反应。TRPC3/TRPC6是电压无关和阳离子非选择性的离子通道，由gq刺激的磷脂酶C激活产生的二酰基甘油激活。然而，这些结果是从体外细胞系统中获得的，使用从新生大鼠分离的心肌细胞进行受体刺激。必须证明TRPC3/TRPC6在体内肥大模型中的重要性。因此，我们研究了TRPC3/TRPC6是否参与了压力过载引起的心脏肥厚。压力过载被认为是人类慢性高血压的小鼠模型，并引起心脏肥厚。由于有选择性抑制TRPC3的化合物Pyr3，我们获得了它并给药给压力过载的小鼠。压力过载是由主动脉横缩术（TAC）施加的，Pyr3是由渗透微型泵施加的。与野生型小鼠相比，pyr3处理小鼠的压力过载诱导的肥大受到抑制，这是通过心肌细胞大小增加和ANP表达增加来评估的。此外，心功能，如缩短分数改善与Pyr3治疗。接下来，我们还研究了TRPC6在压力超载引起的心脏肥厚中的作用。由于TRPC6的磷酸化抑制了TRPC6的功能，我们使用了cGMP选择性磷酸二酯酶（磷酸二酯酶5型：PDE5）抑制剂西地那非来增加心脏cGMP含量。西地那非治疗可抑制压力过载引起的心肌肥厚。西地那非抑制了各种肥厚标记基因表达的增加。在西地那非处理的小鼠中，抗磷酸化TRPC6抗体显示TRPC6在TRPC6介导的Ca^<2+>内流所必需的特定位点磷酸化。这些结果表明，TRPC3/ trpc6介导的Ca^<2+>内流在体内和体外心肌肥厚中起重要作用。少

We have reported that angiotensin II or endothelin-1 stimulation induce hypertrophic responses through transient receptor potential canonical channel 3 (TRPC3) and TRPC6-mediated Ca2+ influx using rat neonatal cardiomyocytes. TRPC3/TRPC6 are voltage-independent and cation-non-selective ion channels, and activated by diacylglycerol generated by Gq-stimulated phospholipase C activation. However, these results were obtained from in vitro cell system using receptor stimulation of cardiomyocytes isolated from newborn rats. It is essential to demonstrate the importance of TRPC3/TRPC6 in in vivo hypertrophy model. Therefore, we have examined whether TRPC3/TRPC6 are involved in pressure overload-induced cardiac hypertrophy. Pressure overload is considered as a mouse model of chronic human hypertension, and induces cardiac hypertrophy. As the compound Pyr3 that selectively inhibits TRPC3 was available, we obtained it and administered to pressure overloaded mice. Pressure overload is applied by … More transverse aortic constriction procedure (TAC), and Pyr3 is administered by osmotic mini-pump. Pressure overload-induced hypertrophy was inhibited in Pyr3-treated mice as compare to wild type mice, which was as assessed by increased size of cardiomyocytes and increased expression of ANP. Furthermore, cardiac function such as fractional shortening is improved by the treatment with Pyr3. Next, we also examined the involvement of TRPC6 in pressure overload-induced cardiac hypertrophy. As the function of TRPC6 is inhibited by phosphorylation of TRPC6, we used a cGMP-selective phosphodiesterase (phosphodiesterase type 5:PDE5) inhibitor, sildenafil, for the increase in cardiac cGMP content. The treatment with sildenafil inhibited cardiac hypertrophy by pressure overload. The increased expression of various marker genes of hypertrophy was inhibited by the treatment with sildenafil. In sidenafil-treated mice, anti-phospho-TRPC6 antibody revealed that TRPC6 was phosphorylated at a specific site that is essential for TRPC6-mediated Ca^<2+> influx. These results suggest that TRPC3/TRPC6-mediated Ca^<2+> influx plays an important role in cardiac hypertrophy in vivo as well as in vitro. Less