Pacemaker shift in the rabbit sinoatrial node in response to vagal nerve stimulation
Pacemaker shift in the rabbit sinoatrial node in response to vagal nerve stimulation
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DOI：
10.1113/eph8602100
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发表时间：
2001-03-01
影响因子：
2.7
通讯作者：
Kodama, I
中科院分区：
文献类型：
--
作者：
Shibata, N;Inada, S;Kodama, I
采用改进的双极高增益低频带通滤波细胞外电位标测系统，观察短暂节后迷走神经刺激对兔窦房结(SA)激活序列的影响，采用逐拍的方法测量心外膜小面积(7 mm×7 mm)的激活序列。从起搏电位的激活顺序和特征形态可以清楚地识别出起搏器的前导部位。迷走神经刺激可使自发频率出现短暂的初始减慢，随后出现较长时间的继发性减慢，在两个减慢时相间有一段短暂的相对或绝对加速，在自发频率的变化过程中，起搏器前导部位沿终脊上下方向以复杂的节拍方式移位1~6 mm。对于刺激后的第一次自发兴奋，减慢越大，起搏器移位的距离越大。起搏速度减慢的程度与起搏器移位距离之间不存在线性关系。迷走神经刺激引起起搏器前导部位的这些变化可能是哺乳动物SA结节在神经支配、受体分布和离子通道密度等方面功能和形态异质性的结果。
Effects of brief postganglonic vagal nerve stimulation on the activation sequence of the rabbit sinoatrial (SA) node were investigated, Activation sequences in a small area (7 mm x 7 mm) on the epicardial surface were measured in a beat-to-beat manner using an extracellular potential mapping system composed of 64 modified bipolar electrodes with high-gain and low-frequency band-pass filtering. The leading pacemaker site was recognised clearly from both the activation sequence and the characteristic morphology of the potentials. Vagal stimulation resulted in a short-lasting initial slowing of spontaneous rate followed by a long-lasting secondary slowing a brief period of relative or absolute acceleration was interposed between the two slowing phases, During these changes of spontaneous rate, the leading pacemaker site shifted in a complex beat-to-beat manner by 1-6 mm alongside the crista terminalis in the superior or inferior direction. For the first spontaneous excitation following stimulation, the greater the slowing, the larger the distance of the pacemaker shift. There was no such linear relationship between the extent of slowing and the distance of pacemaker shift for the subsequent beats. These changes in the leading pacemaker site in response to vagal stimulation may be the result of the functional and morphological heterogeneity of the mammalian SA node in terms of innervation, receptor distribution and ion channel densities.