van Kempen M J, Fromaget C, Gros D, Moorman A F, Lamers W H
Department of Anatomy and Embryology, University of Amsterdam, The Netherlands.
Circ Res. 1991 Jun;68(6):1638-51. doi: 10.1161/01.res.68.6.1638.
The developmental appearance and spatial distribution pattern of gap junctions were studied in prenatal and adult rat hearts. Gap junctions were visualized immunohistochemically with an antibody raised against a unique cytoplasmic epitope of connexin43, and the spatial distribution pattern was determined by three-dimensional reconstruction. The results demonstrate that from embryonic day 13 onward, connexin43 becomes detectable immunohistochemically in the myocardium of atria and ventricles. No expression is initially detectable in the myocardium of the sinus venosus, the sinoatrial node, the posterior wall of the atrium and pulmonary veins, the interatrial septum, the atrioventricular canal, including atrioventricular node and bundle, the interventricular septum, and the outflow tract. The developmental increase in the density of gap junctions in atria and ventricles of prenatal hearts correlates well with the reported developmental increase in conduction velocity. Whereas connexin43 becomes expressed in the derivatives of the sinus venosus (except for the sinoatrial node) and in the subepicardial layer of the ventricular free wall shortly before birth, it remains undetectable in the atrioventricular node and bundle and the proximal part of the ventricular conduction tissue, even in the adult heart. The apparent absence of an abundant expression of connexin43 at a location with a supposedly high conduction velocity (i.e., the atrioventricular bundle and bundle branches) is unexpected. These observations were confirmed in studies of the adult mouse heart, which showed, in addition, that connexin32 is not expressed in any part of the heart.
研究了产前和成年大鼠心脏中间隙连接的发育外观和空间分布模式。使用针对连接蛋白43独特细胞质表位产生的抗体，通过免疫组织化学方法使间隙连接可视化，并通过三维重建确定其空间分布模式。结果表明，从胚胎第13天起，连接蛋白43在心房和心室的心肌中可通过免疫组织化学方法检测到。最初在静脉窦、窦房结、心房后壁和肺静脉、房间隔、房室管（包括房室结和束）、室间隔和流出道的心肌中未检测到表达。产前心脏心房和心室中间隙连接密度的发育性增加与报道的传导速度的发育性增加密切相关。尽管连接蛋白43在出生前不久在静脉窦的衍生物（除窦房结外）和心室游离壁的心外膜下层中表达，但在房室结和束以及心室传导组织的近端部分中仍检测不到，即使在成年心脏中也是如此。在本应具有高传导速度的位置（即房室束和束支）明显缺乏连接蛋白43的大量表达是出乎意料的。这些观察结果在成年小鼠心脏的研究中得到了证实，此外，该研究还表明连接蛋白32在心脏的任何部位均未表达。
