Received November 16, 2007
Revised December 19, 2007
Accepted after revision March 10, 2008
Cardiovascular Control [210]
|
Ponto-medullary transection attenuates central respiratory modulation of sympathetic discharge, heart rate and the baroreceptor reflex in the in situ rat
David M Baekey 1*,
Thomas E Dick 1,
Julian F.R. Paton 2
1 Case Western Reserve University
2 University of Bristol
* To whom correspondence should be addressed. E-mail: david.baekey{at}case.edu.
 |
Abstract |
|---|
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 is due to cross talk between brainstem circuits, we have assessed the role of the pons in both the coordination of respiratory and cardiovascular efferent activities and baroreceptor reflex efficacy. Using the arterially perfused in situ preparation of rat, 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 and respiratory modulation of sympathetic nerve activity (and Traube-Hering waves in arterial pressure) as well as post-inspiratory discharges recorded from vagal efferents were eliminated after pontine transection. We also found that though 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.
Key Words:
Baroreceptor, Respiratory control, Sympathetic activity
