title: 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.
authors.affiliation: Center for Narcolepsy, Sleep and Health Research, M/C 802, University of Illinois at Chicago, 845 South Damen Ave., Chicago, IL 60612, USA. irinatopchiy@yahoo.com
authors.forename: Irina
authors.initials: I
authors.lastname: Topchiy
authors.forename: Miodrag
authors.initials: M
authors.lastname: Radulovacki
authors.forename: Jonathan
authors.initials: J
authors.lastname: Waxman
authors.forename: David W
authors.initials: DW
authors.lastname: Carley
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000502:physiology*; D005246:Feedback; D006321:Heart / Q000502:physiology; D008297:Male; D009434:Neural Pathways / Q000502:physiology; D011149:Pons / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012143:Respiratory Physiological Phenomena; D014630:Vagus Nerve / Q000502:physiology*