Firing properties of identified parasympathetic cardiac neurons in nucleus ambiguus
Firing properties of identified parasympathetic cardiac neurons in nucleus ambiguus
复制标题
DOI：
10.1152/ajpheart.1996.271.6.h2609
复制
发表时间：
1996-12-01
影响因子：
4.8
通讯作者：
Mendelowitz, D
中科院分区：
文献类型：
--
作者：
Mendelowitz, D
这项研究测试了这样一种假设，即疑核中的副交感神经细胞具有起搏样活动，或者这些神经元天生就是沉默的。为了验证这一假说，并检验这些神经元的放电特性，通过预先应用于心脏周围终末的荧光示踪剂的存在来识别副交感神经细胞。应用穿孔膜片钳电生理技术，在体外脑干切片上研究了这些已鉴定的副交感神经细胞的自发放电和去极化诱发放电模式。副交感神经细胞静默。然而，在注入去极化电流时，这些神经元的放电延迟很小，并有尖峰频率适应。超极化预脉冲在去极化诱发的放电之前会引起明显的延迟。钙激活的钾通道阻断剂阿帕明能增加这些神经元去极化激活的放电频率，并抑制后超极化。总之，副交感神经细胞不具有起搏器样的特性，但它们确实具有放电特性，这将使它们能够长时间密切跟踪兴奋性突触的激活。
This study tests the hypothesis that identified parasympathetic cardiac neurons in the nucleus ambiguus possess pacemaker-like activity or, alternatively, that these neurons are inherently silent. To test this hypothesis and to examine the firing properties of these neurons, parasympathetic cardiac neurons were identified by the presence of a fluorescent tracer previously applied to their terminals surrounding the heart. Perforated patch-clamp electrophysiological techniques were used to study the spontaneous and depolarization-evoked firing patterns of these identified parasympathetic cardiac neurons in an in vitro brain stem slice. Parasympathetic cardiac neurons were silent. On injection of depolarizing current, however, these neurons fired with both little delay and spike frequency adaptation. Hyperpolarizing prepulses elicited a significant delay before depolarization-evoked firing. The Ca2+-activated K+ channel blocker apamin, but not charybdotoxin, increased the depolarization-activated firing frequency of these neurons and inhibited the afterhyperpolarization. In summary, parasympathetic cardiac neurons do not have pacemaker-like properties, but they do possess discharge characteristics that would enable them to closely follow excitatory synaptic activation for prolonged periods.