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

我们已经报道了血管紧张素II或内皮素-1刺激通过瞬时受体电位经典通道3（TRPC 3）和TRPC 6介导的Ca 2+内流诱导大鼠新生心肌细胞肥大反应。TRPC 3/TRPC 6是电压非依赖性和阳离子非选择性离子通道，并被Gq刺激的磷脂酶C激活产生的二酰基甘油激活。然而，这些结果是从使用从新生大鼠分离的心肌细胞的受体刺激的体外细胞系统获得的。证明TRPC 3/TRPC 6在体内肥大模型中的重要性是必要的。因此，我们研究了TRPC 3/TRPC 6是否参与压力超负荷诱导的心脏肥大。压力超负荷被认为是慢性人类高血压的小鼠模型，并诱导心脏肥大。由于选择性抑制TRPC 3的化合物Pyr 3是可获得的，我们获得了它并将其施用给压力超负荷小鼠。压力过载通过以下方式施加： 关于我们 横向主动脉缩窄术（TAC），Pyr 3通过渗透微型泵给药。与野生型小鼠相比，Pyr 3处理的小鼠中压力超负荷诱导的肥大被抑制，这通过心肌细胞大小增加和ANP表达增加来评估。此外，通过用Pyr 3处理改善心脏功能，例如缩短分数。接下来，我们还研究了TRPC 6在压力超负荷诱导的心脏肥大中的参与。由于TRPC 6的功能被TRPC 6的磷酸化抑制，我们使用cGMP选择性磷酸二酯酶（磷酸二酯酶5型：PDE 5）抑制剂西地那非来增加心脏cGMP含量。西地那非治疗通过压力超负荷抑制心肌肥厚。西地那非治疗可抑制肥大的各种标志基因的表达增加。在西地那非处理的小鼠中，抗磷酸化TRPC 6抗体显示TRPC 6在TRPC 6介导的Ca^2+内流所必需的特定位点磷酸化。这些结果表明TRPC 3/TRPC 6介导的Ca^2+内流在体内和体外心脏肥大中起重要作用。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