TRPC3 regulates the automaticity of embryonic stem cell-derived cardiomyocytes. (15th January 2016)

• Record Type: Journal Article
• Authors: Qi, Zenghua; Wong, Chun Kit; Suen, Chi Ho; Wang, Jinzhao; Long, Cheng; Sauer, Heinrich; Yao, Xiaoqiang; Tsang, Suk Ying
• Is Part Of: International journal of cardiology. Volume 203(2016)
• Page Start: 169
• Page End: 181
• Publication Date: 2016-01-15
• Subjects: Embryonic stem cell-derived cardiomyocytes -- Canonical transient receptor potential isoform 3 -- Spontaneous action potential -- Phase 4 diastolic depolarization -- Calcium; Cardiology -- Periodicals; Electronic journals; 616.12
• DOI: 10.1016/j.ijcard.2015.10.018
• Languages: English
• ISSNs: 0167-5273

Abstract

Abstract: Background: Cardiac pacemaking is a complex phenomenon that is not completely understood. Canonical transient receptor potential isoform 3 (TRPC3) channel is a cation channel that permeates both Ca 2 + and Na + . TRPC3 was previously found to express in adult cardiomyocytes. However, its role in cardiac pacemaking is unexplored. Here we used mouse embryonic stem cell-derived cardiomyocytes (mESC-CMs) to investigate whether TRPC3 regulates the spontaneous automaticity and the underlying mechanism involved. Methods and results: Immunocytochemistry results showed that TRPC3 is expressed at the T-tubules of mESC-CMs. Whole-cell patch clamping showed that single mESC-CMs contain TRPC3 current. Confocal Ca 2 + imaging showed that the TRPC3-specific blocker Pyr3 decreased Ca 2 + transients and local Ca 2 + release (LCR) of mESC-CMs. Combined current and voltage clamp recordings from the same cell showed that reducing the TRPC3 current, either by Pyr3 or a dominant negative (loss-of-function) construct of TRPC3, decreased the pacemaker activity of mESC-CMs as reflected by a decrease in action potential rate, a depolarized maximum diastolic potential and a decrease in slope of phase 4 diastolic depolarization. Furthermore, decreasing the TRPC3 current diminished, while increasing the TRPC3 current augmented the sodium–calcium exchanger (NCX) current in mESC-CMs. Lastly, decrease in TRPC3 current decreased the phosphorylation of ryanodine receptor isoform 2 at Ser2809 and phospholamban at Thr17. Conclusions: TRPC3 positively regulates diastolic depolarization of spontaneous action potential by increasing LCR and NCX current and therefore is an important determinant in pacemaking of mESC-CMs.