Abstract：
The dorsal motor nucleus of the vagus (DMV) contains parasympathetic motoneurons that project to the heart and lungs. These motoneurons control ventricular excitability/contractility and airways secretions/blood flow, respectively. However, their electrophysiological properties, morphology and synaptic input activity remain unknown. One important ionic current described in DMV motoneurons controlling their electrophysiological behaviour is the A-type mediated by voltage-dependent K+ (Kv) channels. Thus, we compared the electrophysiological properties, synaptic activity, morphology, A-type current density, and single cell expression of Kv subunits, that contribute to macroscopic A-type currents, between DMV motoneurons projecting to either the heart or lungs of adult male rats. Using retrograde labelling, we visualized distinct DMV motoneurons projecting to the heart or lungs in acutely prepared medullary slices. Subsequently, whole cell recordings, morphological reconstruction and single motoneuron qRT-PCR studies were performed. DMV pulmonary motoneurons were more depolarized, electrically excitable, presented higher membrane resistance, broader action potentials and received greater excitatory synaptic inputs compared to cardiac DMV motoneurons. These differences were in part due to highly branched dendritic complexity and lower magnitude of A-type K+ currents. By evaluating expression of channels that mediate A-type currents from single motoneurons, we demonstrated a lower level of Kv4.2 in pulmonary versus cardiac motoneurons, whereas Kv4.3 and Kv1.4 levels were similar. Thus, with the distinct electrical, morphological, and molecular properties of DMV cardiac and pulmonary motoneurons, we surmise that these cells offer a new vista of opportunities for genetic manipulation providing improvement of parasympathetic function in cardiorespiratory diseases such heart failure and asthma.
摘要：
迷走神经(DMV)的背运动核包含投射到心脏和肺的副交感神经运动神经元。这些运动神经元控制心室兴奋性/收缩性和气道分泌物/血流，分别。然而,它们的电生理特性，形态学和突触输入活动仍然未知。DMV运动神经元中描述的控制其电生理行为的一种重要离子电流是由电压依赖性K（Kv）通道介导的A型。因此，我们比较了电生理特性，突触活动，形态学,A型电流密度,和Kv亚基的单细胞表达，有助于宏观A型电流，DMV运动神经元投射到成年雄性大鼠的心脏或肺之间。使用逆行标签，我们在严格准备的髓质切片中可视化了投射到心脏或肺的不同DMV运动神经元。随后，整个细胞记录，进行了形态学重建和单运动神经元qRT-PCR研究。DMV肺运动神经元更去极化，电激发,呈现更高的膜电阻，与心脏DMV运动神经元相比，更广泛的动作电位和接受更多的兴奋性突触输入。这些差异部分是由于高度分支的树枝状复杂性和较低的A型K电流的幅度。通过评估介导来自单个运动神经元的A型电流的通道的表达，我们证明了肺运动神经元和心脏运动神经元的Kv4.2水平较低，而Kv4.3和Kv1.4水平相似。因此，有了独特的电气，形态学,DMV心脏和肺运动神经元的分子特性，我们推测，这些细胞为基因操作提供了新的机会，从而改善了心肺疾病如心力衰竭和哮喘的副交感神经功能。
