Résumé :
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Communication n° 687 Even though sequencing of the mammalian genome has led to the discovery of a large number of ionic channel genes, identification of the molecular determinants of cellular electrical properties in different regions of the heart has been rarely obtained. We developed a high throughput approach capable of simultaneously assessing the expression pattern of ionic channel repertoire from different regions of the mouse heart. By using large-scale real-time RT-PCR, we have profiled 71 channels and related genes in the sino-atrial node (SAN), atrio-ventricular node (AVN), the atria (A) and ventricles (V). Hearts from 30 adult male C57BL/6 mice were micro-dissected and RNA isolated from 6 pools of 5 mice each. TaqMan data were analyzed using the threshold cycle (CT) relative quantification method. Cross-contamination of each region was checked with expression of the atrial and ventricular myosin light chains. Two-way hierarchical clustering analysis of the 71 genes successfully classified the 6 pools from the 4 distinct regions. In comparison with the atrium, the SAN and AVN were characterized by higher expression of Navß1, Navß3, Cav1.3, Cav3.1 and 2 and a lower expression of Kv4.2, Cx40, Cx43 and Kir3.1. In addition, the?2?Cav SAN was characterized by higher expression of HCN1 and HCN4 and lower expression 4. The AVN was characterized by higher expression?of RyR2, Kir6.2, Cavß2 and Cav 7. Other gene expression profile?of Nav1.1, Nav1.7, Kv1.6, Kvß1, MinK and Cav discriminates the ventricular from the atrial myocardium. The present study provides the first genome-scale regional ionic channel expression profile in the mouse heart.
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