Yanling Meng1, Wenyang Li1, Ying Zou1, Ye Yao1, Hong Huang1, Jianjun Sun1, Xiaomeng Li1, Shu Guo2, Xilong Zhang3, Wei Wang1. 1. Institute of Respiratory Disease, The First Hospital of China Medical University, Shenyang, People's Republic of China. 2. Department of Plastic Surgery, The First Hospital of China Medical University, Shenyang, People's Republic of China. 3. Department of Respiratory and Critical Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, People's Republic of China.
Abstract
BACKGROUND: Obstructive sleep apnea (OSA) is characterized by repetitive episodes of upper airway collapse during sleep. The contraction of upper airway dilator muscles plays a crucial role in maintaining UA patency. Chronic intermittent hypoxia (CIH) is the most important pathophysiological process of OSA. Exposure to CIH induced not only the damage of dilator muscles but also the plasticity of the muscles. This study aimed to dynamically assess the influence of CIH on the upper airway. METHODS: The experiments were performed on 44 rats. They were randomly divided into a normoxia (NO) group (n=22) and CIH group (n=22). In each group (n=6, respectively), EMG, transcranial magnetic stimulation (TMS) response, and critical pressure (Pcrit) value were recorded on day 0 (the day before exposure), and the 7th, 14th, 21st, and 28th day of air/CIH exposure. For each group, 16 rats were used for transmission electron microscopy observations on day 0, and the 7th, 14th and 28th day of air/CIH exposure (n=4 for every time point). RESULTS: Compared to the NO group at the same point, the CIH group showed a damaged ultrastructure of genioglossus, increased activity of genioglossus corticomotor area, and increased Pcrit of the upper airway from the 7th to the 28th day of CIH. Increased EMG activity occurred at the 14th day of CIH and lasted for 2 weeks. CONCLUSION: The elevated genioglossus corticomotor excitability in response to the CIH could not counterbalance the damage effect of CIH on upper airway dilator muscles, which ultimately increased the collapsibility of the upper airway.
BACKGROUND: Obstructive sleep apnea (OSA) is characterized by repetitive episodes of upper airway collapse during sleep. The contraction of upper airway dilator muscles plays a crucial role in maintaining UA patency. Chronic intermittent hypoxia (CIH) is the most important pathophysiological process of OSA. Exposure to CIH induced not only the damage of dilator muscles but also the plasticity of the muscles. This study aimed to dynamically assess the influence of CIH on the upper airway. METHODS: The experiments were performed on 44 rats. They were randomly divided into a normoxia (NO) group (n=22) and CIH group (n=22). In each group (n=6, respectively), EMG, transcranial magnetic stimulation (TMS) response, and critical pressure (Pcrit) value were recorded on day 0 (the day before exposure), and the 7th, 14th, 21st, and 28th day of air/CIH exposure. For each group, 16 rats were used for transmission electron microscopy observations on day 0, and the 7th, 14th and 28th day of air/CIH exposure (n=4 for every time point). RESULTS: Compared to the NO group at the same point, the CIH group showed a damaged ultrastructure of genioglossus, increased activity of genioglossus corticomotor area, and increased Pcrit of the upper airway from the 7th to the 28th day of CIH. Increased EMG activity occurred at the 14th day of CIH and lasted for 2 weeks. CONCLUSION: The elevated genioglossus corticomotor excitability in response to the CIH could not counterbalance the damage effect of CIH on upper airway dilator muscles, which ultimately increased the collapsibility of the upper airway.
Authors: David McSharry; Ciara O'Connor; Triona McNicholas; Simon Langran; Michael O'Sullivan; Madeleine Lowery; Walter T McNicholas Journal: Respir Physiol Neurobiol Date: 2012-06-04 Impact factor: 1.931
Authors: Toshiyuki Ogasa; Andrew D Ray; Charles P Michlin; Gaspar A Farkas; Brydon J B Grant; Ulysses J Magalang Journal: Am J Respir Crit Care Med Date: 2004-07-15 Impact factor: 21.405
Authors: Andrew D Ray; Ulysses J Magalang; Charles P Michlin; Toshiyuki Ogasa; John A Krasney; Luc E Gosselin; Gaspar A Farkas Journal: Am J Physiol Regul Integr Comp Physiol Date: 2007-04-25 Impact factor: 3.619