title: Changes in vascular properties, not ventricular properties, predominantly contribute to baroreflex regulation of arterial pressure.
abstract: Baroreflex modulates both the ventricular and vascular properties and stabilizes arterial pressure (AP). However, how changes in those mechanical properties quantitatively impact the dynamic AP regulation remains unknown. We developed a framework of circulatory equilibrium, in which both venous return and cardiac output are expressed as functions of left ventricular (LV) end-systolic elastance (Ees), heart rate (HR), systemic vascular resistance (R), and stressed blood volume (V). We investigated the contribution of each mechanical property using the framework of circulatory equilibrium. In six anesthetized dogs, we vascularly isolated carotid sinuses and randomly changed carotid sinus pressure (CSP), while measuring the LV Ees, aortic flow, right and left atrial pressure, and AP for at least 60 min. We estimated transfer functions from CSP to Ees, HR, R, and V in each dog. We then predicted these parameters in response to changes in CSP from the transfer functions using a data set not used for identifying transfer functions and predicted changes in AP using the equilibrium framework. Predicted APs matched reasonably well with those measured (r2=0.85-0.96, P<0.001). Sensitivity analyses indicated that Ees and HR (ventricular properties) accounted for 14±4 and 4±2%, respectively, whereas R and V (vascular properties) accounted for 32±4 and 39±4%, respectively, of baroreflex-induced AP regulation. We concluded that baroreflex-induced dynamic AP changes can be accurately predicted by the transfer functions from CSP to mechanical properties using our framework of circulatory equilibrium. Changes in the vascular properties, not the ventricular properties, predominantly determine baroreflex-induced AP regulation.
authors.affiliation: Department of Cardiovascular Medicine, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan; tsaka@cardiol.med.kyushu-u.ac.jp.
authors.forename: Takafumi
authors.initials: T
authors.lastname: Sakamoto
authors.affiliation: Department of Cardiovascular Medicine, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan;
authors.forename: Takamori
authors.initials: T
authors.lastname: Kakino
authors.affiliation: Department of Cardiovascular Medicine, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan;
authors.forename: Kazuo
authors.initials: K
authors.lastname: Sakamoto
authors.affiliation: Iizuka Hospital, Fukuoka, Japan; and.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Tobushi
authors.affiliation: Munakata Suikoukai General Hospital, Fukuoka, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Tanaka
authors.affiliation: Department of Cardiovascular Medicine, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan;
authors.forename: Keita
authors.initials: K
authors.lastname: Saku
authors.affiliation: Department of Cardiovascular Medicine, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan;
authors.forename: Kazuya
authors.initials: K
authors.lastname: Hosokawa
authors.affiliation: Department of Cardiovascular Medicine, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan;
authors.forename: Ken
authors.initials: K
authors.lastname: Onitsuka
authors.affiliation: Department of Cardiovascular Medicine, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan;
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Murayama
authors.affiliation: Iizuka Hospital, Fukuoka, Japan; and.
authors.forename: Takaki
authors.initials: T
authors.lastname: Tsutsumi
authors.affiliation: Department of Cardiovascular Medicine, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan;
authors.forename: Tomomi
authors.initials: T
authors.lastname: Ide
authors.affiliation: Department of Cardiovascular Medicine, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan;
authors.forename: Kenji
authors.initials: K
authors.lastname: Sunagawa
mesh_terms: D000818:Animals; D001011:Aorta / Q000502:physiology*; D062186:Arterial Pressure; D016279:Atrial Function, Left; D062185:Atrial Pressure; D017704:Baroreflex; D001810:Blood Volume; D002346:Carotid Sinus / Q000294:innervation*; D004285:Dogs; D006339:Heart Rate; D006706:Homeostasis; D040542:Mechanotransduction, Cellular; D008955:Models, Cardiovascular; D013997:Time Factors; D014655:Vascular Resistance; D016277:Ventricular Function, Left
keywords: baroreflex; circulatory equilibrium; hemodynamics; transfer function