E ffects of periodic and sustained stretching on cardiac culture

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/69374

Title:	E ffects of periodic and sustained stretching on cardiac culture
Authors:	劉閔禎;Liu,Ming-Chen
Contributors:	生物物理研究所
Keywords:	心臟;心肌細胞;拉伸;周期拉伸;持續拉伸;拉伸激活通道;機械力敏感通道;纖維母細胞;cardiac;cardiomyocyte;stretch;fibroblast;periodic stretching;sustained stretching;stretch-activated ion channel;SACs;Gadolinium
Date:	2016-01-05
Issue Date:	2016-03-17 19:32:07 (UTC+8)
Publisher:	國立中央大學
Abstract:	一般來說我們認為心臟跳動是藉由電訊號傳遞來控制的。但是研究發現除了電訊號之外，機械力也能夠誘導心肌細胞上的機械力敏感離子通道開啟並且產生電流進而影響心臟的電活動。本實驗主要是探討機械力對心臟細胞跳動週期的影響，另外我們也探討纖維母細胞的數量多寡是否影響跳動週期。心臟細胞是由大鼠胚胎（懷孕17天）的心臟取得，並且培養在可變形的腔室中，我們以單軸方向拉腔室。本實驗使用了兩種形式來拉伸細胞：(1) 週期性拉伸：1 Hz下持續二到四個小時，並以鈣離子螢光染色來觀察細胞跳動，(2) 持續性拉伸：將腔室維持在拉的情況下五分鐘再放掉腔室，並在明視野顯微鏡下觀測。本實驗使用了拉伸激活離子通道阻斷劑：釓(Gd3+)，這是一個應用在機械力敏感通道上常見的阻斷劑。心臟細胞在週期性拉伸過後，我們發現細胞的跳動週期會接近拉伸的週期。在持續性拉伸下，細胞的跳動週期變長。加入釓之後我們發現，拉伸對細胞跳動週期的影響小很多。除此之外，本實驗抑制了纖維母細胞的增長，發現在低密度纖維母細胞的情況下，跳動週期以及心律變異度明顯的高於高密度纖維母細胞的心臟細胞。 ;Traditionally, it is believed that cardiac dynamics is controlled only by electrical activities. However, it is known that mechanical forces can also activate mechanical sensitive channels in the cell which can bring changes in electrical activity. The purpose of our experiment is to understand whether mechanical forces affect the cardiac beating dynamics. We also want to understand whether the number of fibroblasts which is mechanical sensitive affect the beating dynamics. Cardiomyocytes were dissected from rat embryos and seeded on a deformable silicon chamber in which stretching can be realized by elongation. Two kinds of stretching were used: (1) Periodic stretching at 1 Hz for 2 to 4 hours and the dynamics are observed by calcium imaging, (2) Sustained stretching for 5 minutes and the dynamics are observed by bright field microscopy. The stretch-activated ion channels (SACs) blocker, Gadolinium (Gd3+), was used in our experiment to investigate its effect on the beating dynamics. Under periodic stretching, we found that the frequency of cardiomyocytes can almost be synchronized by the stretching frequency. As for sustained stretching, we found that the heart rate decreases during stretching. After treating with $Gd^{3+}$, the difference of inter-beat interval (IBI) between stretched and non-stretched samples significantly decreases. In addition, we also investigated the beating of cardiac culture in the presence of high and low density fibroblasts. As for low density of fibroblasts, the IBI and heart rate variability is higher than those in the high density one.
Appears in Collections:	[Graduate Institute of Biophysics] Electronic Thesis & Dissertation

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