DIFFERENT MECHANISMS OF CONTRACTION GENERATION IN CIRCULAR MUSCLE OF CANINE COLON
DIFFERENT MECHANISMS OF CONTRACTION GENERATION IN CIRCULAR MUSCLE OF CANINE COLON
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DOI：
10.1152/ajpgi.1989.256.3.g570
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发表时间：
1989-03-01
影响因子：
--
通讯作者：
HUIZINGA, JD
中科院分区：
文献类型：
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作者：
BARAJASLOPEZ, C;HUIZINGA, JD
狗结肠环形肌层的平滑肌细胞显示出 -44 mV 的机械阈值。在来自粘膜下层和肌间神经丛表面的细胞之间没有测量到机械阈值的梯度。在来自粘膜下表面的细胞的自发慢波活动的上冲程和平台期期间以及主要发生在肌间神经丛表面的细胞和零星地发生在粘膜下表面的细胞中的尖峰电位期间超过了阈值。卡巴胆碱引起的电和机械活动的具体变化被钙内流阻断所抑制，具体如下：1）慢波持续时间增加； 2）平台电位下降； 3) 增强扣球活性； 4) 收缩力增加。这表明在环状肌层两个表面的细胞中存在卡巴胆碱时，钙流入显着增加。钙流入的增加可能是卡巴胆碱对钙电导的直接作用的结果和/或可能是由外向电流的减少介导的。后者由与输入电阻增加相关的卡巴胆碱诱导的膜去极化表明，这两种情况对甲氧基维拉帕米均不敏感。结果表明，兴奋性刺激可以通过不同的电生理活动产生环形肌的收缩。此外，自发电活动的模式和对卡巴胆碱刺激的不同反应提供了有关结肠环形肌层内电活动的异质性的进一步信息。
Smooth muscle cells from the circular muscle layer of the dog colon showed a mechanical threshold of -44 mV. No gradient in mechanical threshold was measured between the cells from the submucosal and myenteric plexus surface. The threshold was passed during the upstroke and the plateau phase of the spontaneous slow-wave activity from cells at the submucosal surface and by spike potentials occurring mainly in cells at the myenteric plexus surface and sporadically in cells at the submucosal surface. Carbachol-induced specific changes in electrical and mechanical activities that were inhibited by calcium influx blockade are as follows: 1) increase in slow-wave duration; 2) decrease in plateau potential; 3) enhancement of spiking activity; and 4) increase in contractility. This indicates that calcium influx is significantly increased in the presence of carbachol in cells at both surfaces of the circular muscle layer. The increase in calcium influx could be the result of a direct action by carbachol on the calcium conductance and/or could be mediated by a decrease in outward current. The latter is suggested by the carbachol-induced membrane depolarization associated with an increase in the input resistance, which were both methoxyverapamil insensitive. The results show that an excitatory stimulus can generate contraction of the circular muscle through different electrophysiological activities. In addition, the patterns of spontaneous electrical activity and the different responses to carbachol stimulation provide further information about the heterogenenous nature of the electrical activities within the colonic circular muscle layer.