The Role Of Cardiac Stromal Cells In Arrhythmia

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The subcellular mechanisms of fatal arrhythmia such as ventricular flutter and fibrillation are unknown. The purpose of this study is to clarify the role of cardiac stromal cells in these type of arrhythmia. So I investigated regulation of intracellular calcium ion concentration ([Ca^<2+>]_i) in abnormally high [Ca^<2+>]_i and propagation of calcium wave between heart muscle cells and stromal cells. The results obtained in this study are as follow,1) The elevation of diastolic [Ca^<2+>]_i per se directly influenced the [Ca^<2+>]_i-regulation by sarcoplasmic reticulum.2) Confocal images enabled to determine the cell-to-cell junction between clustered heart muscle cells of guinea pig and revealed that the high [Ca^<2+>]_i can evoke calcium-induced calcium release from the sarcoplasmic reticulum in the neighboring heart muscle cells through the gap junction.3) Calcium wave did not propagate between co-cultured heart muscle cells and stromal cells although co-excitation was recognized.4) Ischemia induced temporally abnormal expression of connexin 43 at the edge of the cardiomyocytes bordering the infarcted area.