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Ponto‐medullary transection attenuates sympathorespiratory coupling and eliminates cardiac sinus arrhythmia in the in situ rat
Author(s) -
Baekey David M,
Dick Thomas E,
Paton Julian FR
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.739.6
Subject(s) - pons , brainstem , vagus nerve , respiratory system , heart rate , medicine , medulla , vagal tone , autonomic nervous system , anatomy , medulla oblongata , cardiology , blood pressure , central nervous system , stimulation
Sympathetic nerve activity obtained from experimental animals demonstrates a pronounced modulation with the central respiratory rhythm. This modulation is mirrored in heart rate (respiratory sinus arrhythmia) and arterial pressure (Hering‐Traube waves) that are common to all mammals. The neural substrate responsible for sympatho‐respiratory coupling has not yet been defined. Based on recent evidence, we hypothesized that pontine neuron populations may be key components for this synchrony. Using the arterially perfused in situ preparation of rat, we recorded neural activities from the left phrenic nerve, central end of the vagus nerve and thoracic sympathetic chain (T8‐T10), as well as heart rate. Following a control period, the brainstem was transected transversely at the rostral edge of the facial nucleus, separating the pons and medulla. Respiration remained rhythmic but apneustic, with an increase of inspiratory duration. Both post‐inspiratory activity in the vagus nerve and the cardiac sinus arrhythmia were abolished while the synchronization of sympathetic outflow with the central respiratory signal was reduced substantially both in amplitude and duration. We surmise that descending drives from the pons are critical for the normal coupling of respiratory related modulations of sympathetic outflows destined for the heart and vasculature. Funded by the Leverhulme Trust (University of Bristol).