Impact of the vagal feedback on cardiorespiratory coupling in anesthetized rats

Abstract

Cardiorespiratory coupling can be significantly influenced by both pontine and vagal modulation of medullary motor and premotor areas. We investigated influences of the pontine intertrigeminal region (ITR) and peripheral vagal pathways on the coupling between systolic blood pressure (SBP) and respiration in 9 anesthetized rats. Glutamate injection into the ITR perturbed both respiration and SBP and decreased SBP-respiratory coherence (0.95±0.01 vs 0.89±0.02; (p=0.01). Intravenous infusion of serotonin (5-HT) produced apnea and hypertension and also decreased SBP-respiratory coherence (0.95±0.01 vs 0.72±0.06; p=0.04). Bilateral vagotomy eliminated the cardiorespiratory coherence perturbations induced by central (glutamate injection into the ITR: 0.89±0.03 vs 0.86±0.03; p=0.63) and peripheral (5-HT infusion: 0.89±0.03 vs 0.88±0.02; p=0.98) pharmacologic manipulations. Glutamate stimulation of the ITR postvagotomy increased the relative spectral power density of SBP in the respiratory frequency range (0.25±0.08 vs 0.55±0.06; p=0.01). The data suggest that SBP-respiratory coupling is largely mediated within the central nervous system, with vagal systems acting in a way that disrupts coherence during transient cardiorespiratory disturbances. Although decreased cardiorespiratory coherence may increase cardiac work during perturbations, this may be physiologically advantageous in restoring homeostatic equilibrium of respiration and blood pressure.

Self-Regulation of Breathing as a Primary Treatment for Anxiety

“…The study proposed that if stimulation of the vagus nerve were to be repeated, before the last inhibition response ended then sustained inhibition may be maintained (Zagon and Kemeny 2000). Animal studies have shown cardiorespiratory coupling ceases after bilateral vagotomy, suggesting that cardiorespiratory synchronization is mediated by the vagus nerve, which imparts parasympathetic control (Campbell and Egginton 2007;Dick et al 2009;Topchiy et al 2011). In addition, schizophrenic patients exhibit decreased levels of cardiorespiratory synchronization, which indicates decreased vagal modulation and inhibition in the brainstem (Peupelmann et al 2009).…”