• Júlia G V de Souza, Daniel P de Souza, Carlos A A da Silva, Renato W Martins Sá, PatonJulian F RJFRManaaki Manawa - The Centre for Heart Research, Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand., Melina P da Silva, and MoraesDavi J ADJADepartment of Physiology and Biophysics, Biomedical Science Institute, University of São Paulo, São Paulo, SP, Brazil. Electronic address: davimoraes@icb.usp.br..
• School of Medicine of Ribeirão Preto, Department of Physiology, University of São Paulo, Ribeirão Preto, SP, Brazil.
• Neuroscience. 2024 Jul 23; 551: 153165153-165.

AbstractThe 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.Copyright © 2024 IBRO. Published by Elsevier Inc. All rights reserved.

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