Segers L S, Nuding S C, Vovk A, Pitts T, Baekey D M, O'Connor R, Morris K F, Lindsey B G, Shannon R, Bolser Donald C
Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida Tampa, FL, USA.
Front Physiol. 2012 Jun 29;3:223. doi: 10.3389/fphys.2012.00223. eCollection 2012.
This study investigated the stability of the discharge identity of inspiratory decrementing (I-Dec) and augmenting (I-Aug) neurons in the caudal (cVRC) and rostral (rVRC) ventral respiratory column during repetitive fictive cough in the cat. Inspiratory neurons in the cVRC (n = 23) and rVRC (n = 17) were recorded with microelectrodes. Fictive cough was elicited by mechanical stimulation of the intrathoracic trachea. Approximately 43% (10 of 23) of I-Dec neurons shifted to an augmenting discharge pattern during the first cough cycle (C1). By the second cough cycle (C2), half of these returned to a decrementing pattern. Approximately 94% (16 of 17) of I-Aug neurons retained an augmenting pattern during C1 of a multi-cough response episode. Phrenic burst amplitude and inspiratory duration increased during C1, but decreased with each subsequent cough in a series of repetitive coughs. As a step in evaluating the model-driven hypothesis that VRC I-Dec neurons contribute to the augmentation of inspiratory drive during cough via inhibition of VRC tonic expiratory neurons that inhibit premotor inspiratory neurons, cross-correlation analysis was used to assess relationships of tonic expiratory cells with simultaneously recorded inspiratory neurons. Our results suggest that reconfiguration of inspiratory-related sub-networks of the respiratory pattern generator occurs on a cycle-by-cycle basis during repetitive coughing.
本研究调查了在猫的重复性假咳过程中，尾侧（cVRC）和头侧（rVRC）腹侧呼吸柱中吸气递减（I-Dec）和递增（I-Aug）神经元放电特征的稳定性。用微电极记录cVRC（n = 23）和rVRC（n = 17）中的吸气神经元。通过机械刺激胸段气管诱发假咳。在第一个咳嗽周期（C1）中，约43%（23个中的10个）的I-Dec神经元转变为递增放电模式。到第二个咳嗽周期（C2）时，其中一半又恢复为递减模式。在多次咳嗽反应发作的C1期间，约94%（17个中的16个）的I-Aug神经元保持递增模式。在C1期间，膈神经爆发幅度和吸气持续时间增加，但在一系列重复性咳嗽中，随后每次咳嗽时均降低。作为评估模型驱动假说（即VRC的I-Dec神经元通过抑制抑制运动前吸气神经元的VRC紧张性呼气神经元来促进咳嗽时吸气驱动的增强）的一个步骤，采用互相关分析来评估紧张性呼气细胞与同时记录的吸气神经元之间的关系。我们的结果表明，在重复性咳嗽过程中，呼吸模式发生器中与吸气相关的子网络在逐个周期的基础上发生重新配置。
