Relative contributions of connexins 40 and 43 to atrial impulse propagation in synthetic strands of neonatal and fetal murine cardiomyocytes
Relative contributions of connexins 40 and 43 to atrial impulse propagation in synthetic strands of neonatal and fetal murine cardiomyocytes
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DOI：
10.1161/01.res.0000250607.34498.b4
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发表时间：
2006-11-24
影响因子：
20.1
通讯作者：
Kleber, Andre G.
中科院分区：
文献类型：
--
作者：
Beauchamp, Philippe;Yamada, Kathryn A.;Kleber, Andre G.
心房组织表达连接蛋白40 （Cx40）和43 （Cx43）蛋白。为了评估Cx40和Cx43在心房电传播中的相对作用，我们合成了来自Cx40或Cx43基因表达缺陷小鼠的培养心房肌细胞链，并通过电压敏感染料荧光的高分辨率光学作图测量了传播速度（PV）。用免疫组化法测定间隙连接中Cx40和/或Cx43的量，用免疫印迹法测定总Cx43或Cx40蛋白量。在Cx43（+/+）培养中，Cx43基因表达的逐渐减少使PV从34 +/- 6 cm/sec降低到30 +/- 8 cm/sec，在Cx43（-/-）培养中降低到19 +/- 11 cm/sec。同时，Cx40免疫信号在间隙连接中占据的细胞面积从Cx43（+/+）的2.0 +/- 1.6%下降到Cx43（+/-）的1.7 +/- 0.5%和Cx43（-/-）链的1.0 +/- 0.2%。相比之下，Cx40表达的逐渐遗传减少使PV从Cx40（+/+）的30 +/- 2 cm/sec增加到Cx40（+/-）的40 +/- 7 cm/sec和Cx40（-/-）的45 +/- 10 cm/sec。同时，Cx43免疫信号在间隙连接中占据的细胞面积从Cx40（+/+）的1.2 +/- 0.9%增加到Cx40（+/-）的2.8 +/- 1.4%和Cx40（-/-）的3.1 +/- 0.6%。与免疫染色结果一致，Triton x -100不溶性部分的免疫印迹显示，cx40消融后的心房提取物中间隙连接中的Cx43增加，而细胞中的Cx43总量保持不变。我们的研究结果表明，Cx43和Cx40的相对丰度是新生儿心脏心房冲动传播的重要决定因素，Cx40的优势降低，而Cx43的优势增加了局部传播速度。
Atrial tissue expresses both connexin 40 (Cx40) and 43 (Cx43) proteins. To assess the relative roles of Cx40 and Cx43 in atrial electrical propagation, we synthesized cultured strands of atrial myocytes derived from mice with genetic deficiency in Cx40 or Cx43 expression and measured propagation velocity (PV) by high-resolution optical mapping of voltage-sensitive dye fluorescence. The amount of Cx40 and/or Cx43 in gap junctions was measured by immunohistochemistry and total or sarcolemmal Cx43 or Cx40 protein by immunoblotting. Progressive genetic reduction in Cx43 expression decreased PV from 34 +/- 6 cm/sec in Cx43(+/+) to 30 +/- 8 cm/sec in Cx43(+/-) and 19 +/- 11 cm/sec in Cx43(-/-) cultures. Concomitantly, the cell area occupied by Cx40 immunosignal in gap junctions decreased from 2.0 +/- 1.6% in Cx43(+/+) to 1.7 +/- 0.5% in Cx43(+/-) and 1.0 +/- 0.2% in Cx43(-/-) strands. In contrast, progressive genetic reduction in Cx40 expression increased PV from 30 +/- 2 cm/sec in Cx40(+/+) to 40 +/- 7 cm/sec in Cx40(+/-) and 45 +/- 10 cm/sec in Cx40(-/-) cultures. Concomitantly, the cell area occupied by Cx43 immunosignal in gap junctions increased from 1.2 +/- 0.9% in Cx40(+/+) to 2.8 +/- 1.4% in Cx40(+/-) and 3.1 +/- 0.6% in Cx40(-/-) cultures. In accordance with the immunostaining results, immunoblots of the Triton X-100-insoluble fraction revealed an increase of Cx43 in gap junctions in extracts from Cx40-ablated atria, whereas total cellular Cx43 remained unchanged. Our results suggest that the relative abundance of Cx43 and Cx40 is an important determinant of atrial impulse propagation in neonatal hearts, whereby dominance of Cx40 decreases and dominance of Cx43 increases local propagation velocity.