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Pontomedullary transection attenuates central respiratory modulation of sympathetic discharge, heart rate and the baroreceptor reflex in the in situ rat preparation
Author(s) -
Baekey David M.,
Dick Thomas E.,
Paton Julian F. R.
Publication year - 2008
Publication title -
experimental physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0958-0670
DOI - 10.1113/expphysiol.2007.041400
Subject(s) - baroreceptor , baroreflex , efferent , pons , medicine , respiratory system , reflex , vagus nerve , heart rate , reflex bradycardia , brainstem , carotid sinus , efferent nerve , anesthesia , vagal tone , bradycardia , autonomic nervous system , cardiology , blood pressure , afferent , stimulation
Previous studies have indicated a major role for the pons in the genesis of the respiratory pattern. The respiratory rhythm is coupled to the cardiovascular system to ensure optimal matching of minute ventilation and cardiac output. Since much of this coupling results from cross‐talk between brainstem circuits, we have assessed the role of the pons in both the co‐ordination of respiratory and cardiovascular efferent activities and the baroreceptor reflex efficacy. Using the arterially perfused in situ rat preparation, we recorded neural activities from the left phrenic nerve, central end of the vagus nerve, thoracic sympathetic chain (T8–T10) and heart rate. Respiratory sinus arrhythmia, respiratory modulation of sympathetic nerve activity (and Traube–Hering waves in arterial pressure) and postinspiratory discharges recorded from vagal efferents were eliminated after pontine transection. We also found that although the sympathetic arterial baroreflex remained intact, respiratory gating of the baroreceptor reflex (i.e. both bradycardia and sympathoinhibition) was abolished after pontine removal. We propose that neural activity of the pons is essential for physiological coupling of centrally generated respiratory and cardiovascular efferent activities.