McArthur Lisa, Chilton Lisa, Smith Godfrey L, Nicklin Stuart A
*Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, U.K.
Biochem Soc Trans. 2015 Jun;43(3):513-8. doi: 10.1042/BST20150035.
Gap junctions are channels which allow electrical signals to propagate through the heart from the sinoatrial node and through the atria, conduction system and onwards to the ventricles, and hence are essential for co-ordinated cardiac contraction. Twelve connexin (Cx) proteins make up one gap junction channel, of which there are three main subtypes in the heart; Cx40, Cx43 and Cx45. In the cardiac myocyte, gap junctions are present mainly at the intercalated discs between neighbouring myocytes, and assist in rapid electrical conduction throughout the ventricular myocardium. Fibroblasts provide the structural skeleton of the myocardium and fibroblast numbers significantly increase in heart disease. Fibroblasts also express connexins and this may facilitate heterocellular electrical coupling between myocytes and fibroblasts in the setting of cardiac disease. Interestingly, cardiac fibroblasts have been demonstrated to increase Cx43 expression in experimental models of myocardial infarction and functional gap junctions between myocytes and fibroblasts have been reported. Therefore, in the setting of heart disease enhanced cardiac myocyte: fibroblast coupling may influence the electrical activity of the myocyte and contribute to arrhythmias.
缝隙连接是允许电信号从窦房结通过心脏、心房、传导系统并继续传导至心室的通道，因此对于心脏的协调收缩至关重要。十二个连接蛋白（Cx）构成一个缝隙连接通道，其中在心脏中有三种主要亚型；Cx40、Cx43和Cx45。在心肌细胞中，缝隙连接主要存在于相邻心肌细胞之间的闰盘处，并有助于在整个心室心肌中进行快速电传导。成纤维细胞提供心肌的结构框架，并且在心脏病中其数量会显著增加。成纤维细胞也表达连接蛋白，这可能会促进心脏病情况下心肌细胞与成纤维细胞之间的异细胞电偶联。有趣的是，在心肌梗死的实验模型中已证明心脏成纤维细胞可增加Cx43的表达，并且已报道了心肌细胞与成纤维细胞之间存在功能性缝隙连接。因此，在心脏病情况下，增强的心肌细胞：成纤维细胞偶联可能会影响心肌细胞的电活动并导致心律失常。
