title: Stimulation of the cardiopulmonary baroreflex enhances ventricular contractility in awake dogs: a mathematical analysis study.
abstract: The cardiopulmonary baroreflex responds to an increase in central venous pressure (CVP) by decreasing total peripheral resistance and increasing heart rate (HR) in dogs. However, the direction of ventricular contractility change is not well understood. The aim was to elucidate the cardiopulmonary baroreflex control of ventricular contractility during normal physiological conditions via a mathematical analysis. Spontaneous beat-to-beat fluctuations in maximal ventricular elastance (Emax), which is perhaps the best available index of ventricular contractility, CVP, arterial blood pressure (ABP), and HR were measured from awake dogs at rest before and after β-adrenergic receptor blockade. An autoregressive exogenous input model was employed to jointly identify the three causal transfer functions relating beat-to-beat fluctuations in CVP to Emax (CVP → Emax), which characterizes the cardiopulmonary baroreflex control of ventricular contractility, ABP to Emax, which characterizes the arterial baroreflex control of ventricular contractility, and HR to Emax, which characterizes the force-frequency relation. The CVP → Emax transfer function showed a static gain of 0.037 ± 0.010 ml(-1) (different from zero; P < 0.05) and an overall time constant of 3.2 ± 1.2 s. Hence, Emax would increase and reach steady state in ∼16 s in response to a step increase in CVP, without any change to ABP or HR, due to the cardiopulmonary baroreflex. Following β-adrenergic receptor blockade, the CVP → Emax transfer function showed a static gain of 0.0007 ± 0.0113 ml(-1) (different from control; P < 0.10). Hence, Emax would change little in steady state in response to a step increase in CVP. Stimulation of the cardiopulmonary baroreflex increases ventricular contractility through β-adrenergic receptor system mediation.
authors.affiliation: Department of Physiology and Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, Michigan; and.
authors.forename: Javier A
authors.initials: JA
authors.lastname: Sala-Mercado
authors.affiliation: Department of Electrical and Computer Engineering, Michigan State University, East Lansing, Michigan.
authors.forename: Mohsen
authors.initials: M
authors.lastname: Moslehpour
authors.affiliation: Department of Physiology and Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, Michigan; and.
authors.forename: Robert L
authors.initials: RL
authors.lastname: Hammond
authors.affiliation: Department of Physiology and Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, Michigan; and.
authors.forename: Masashi
authors.initials: M
authors.lastname: Ichinose
authors.affiliation: Department of Electrical and Computer Engineering, Michigan State University, East Lansing, Michigan.
authors.forename: Xiaoxiao
authors.initials: X
authors.lastname: Chen
authors.affiliation: Department of Physiology and Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, Michigan; and.
authors.forename: Sell
authors.initials: S
authors.lastname: Evan
authors.affiliation: Department of Physiology and Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, Michigan; and.
authors.forename: Donal S
authors.initials: DS
authors.lastname: O'Leary
authors.affiliation: Department of Electrical and Computer Engineering, Michigan State University, East Lansing, Michigan rama@egr.msu.edu.
authors.forename: Ramakrishna
authors.initials: R
authors.lastname: Mukkamala
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D017704:Baroreflex / Q000187:drug effects; D002496:Central Venous Pressure; D004285:Dogs; D006339:Heart Rate; D006352:Heart Ventricles / Q000294:innervation*; D006439:Hemodynamics / Q000187:drug effects; D023421:Models, Animal; D008955:Models, Cardiovascular; D009200:Myocardial Contraction / Q000187:drug effects; D011311:Pressoreceptors / Q000187:drug effects / Q000502:physiology*; D013997:Time Factors; D014655:Vascular Resistance; D014851:Wakefulness
chemical_list: D000319:Adrenergic beta-Antagonists
keywords: beat-to-beat variability; cardiopulmonary baroreflex; maximal ventricular elastance; system identification; ventricular contractility