Tranum-Jensen J, Wilde A A, Vermeulen J T, Janse M J
Anatomy Department C, Panum Institute, University of Copenhagen, Denmark.
Circ Res. 1991 Aug;69(2):429-37. doi: 10.1161/01.res.69.2.429.
Purkinje fiber-ventricular muscle (PV) junctions were identified by extracellular recording in isolated, superfused preparations from rabbit and pig hearts. Microelectrode recordings from different cell types at the PV junctions were obtained, and the cells recorded from were retrieved microscopically. To this end 26 tissue blocks were serially sectioned at 4 microns. Microscopic identification of the very cell recorded from was obtained in five of seven Purkinje, five of 16 transitional, and two of two ventricular muscle cell recordings. In addition, some tissue blocks from both junctional and nonjunctional sites identified only by extracellular recording were examined in serial sections. Transitional cells in the rabbit heart are thin, broad bandlike cells (30-35 by 3-5 microns) arranged in one or two sheets in the subendocardium between the Purkinje layer and ventricular mass. Transitional cells are coupled via short, thin strands to both Purkinje and ventricular muscle cells. A second type of PV coupling was observed frequently in the pig, but in only one of 21 cases in the rabbit. Here, a short, linear segment of small transitional cells connected large-diameter Purkinje cells to ventricular muscle cells. Distances found between Purkinje-transitional cell coupling sites and transitional cell-ventricular muscle coupling sites varied from 100 to 1,000 microns in the rabbit heart and from 50 to several hundred micrometers in the pig heart. Action potentials from transitional cells typically showed multiple components in their upstroke. Both our morphological and electrophysiological findings are compatible with the existence of a relatively high-resistance barrier between Purkinje and transitional cells and between transitional and ventricular muscle cells.
通过对兔和猪心脏分离的、灌注的标本进行细胞外记录来识别浦肯野纤维 - 心室肌（PV）连接。在PV连接处从不同细胞类型进行微电极记录，并通过显微镜检索所记录的细胞。为此，将26个组织块连续切成4微米厚的切片。在7个浦肯野细胞记录中的5个、16个过渡细胞记录中的5个以及2个心室肌细胞记录中的2个中，通过显微镜识别出了所记录的具体细胞。此外，对仅通过细胞外记录识别出的连接部位和非连接部位的一些组织块进行了连续切片检查。兔心脏中的过渡细胞是薄的、宽带状细胞（30 - 35×3 - 5微米），在内皮下层的浦肯野层和心室肌之间以一层或两层排列。过渡细胞通过短而细的纤维与浦肯野细胞和心室肌细胞相连。在猪中经常观察到第二种类型的PV连接，但在兔中21例中仅1例出现。在这里，一小段短的、线性排列的小过渡细胞将大直径的浦肯野细胞与心室肌细胞相连。在兔心脏中，浦肯野细胞 - 过渡细胞连接部位与过渡细胞 - 心室肌连接部位之间的距离在100至1000微米之间，在猪心脏中为50至几百微米。过渡细胞的动作电位在其上升支通常显示多个成分。我们的形态学和电生理学发现均与浦肯野细胞和过渡细胞之间以及过渡细胞和心室肌细胞之间存在相对高电阻屏障的情况相符。
