title: Dynamics of sympathetic baroreflex control of arterial pressure in rats.
abstract: By a white noise approach, we characterized the dynamics of the sympathetic baroreflex system in 11 halothane-anesthetized rats. We measured sympathetic nerve activity (SNA) and systemic arterial pressure (SAP), while carotid sinus baroreceptor pressure (BRP) was altered randomly. We estimated the transfer functions from BRP to SNA (mechanoneural arc), from SNA to SAP (neuromechanical arc), and from BRP to SAP (total arc). The gain of the mechanoneural arc gradually increased about threefold as the frequency of BRP change increased from 0.01 to 0.8 Hz. In contrast, the gain of the neuromechanical arc rapidly decreased to 0.4% of the steady-state gain as the frequency increased from 0.01 to 1 Hz. Although the total arc also had low-pass characteristics, the rate of attenuation in its gain was significantly slower than that of the neuromechanical arc, reflecting the compensatory effect of the mechanoneural arc for the sluggish response of the neuromechanical arc. We conclude that the quantitative estimation of the baroreflex dynamics is vital for an integrative understanding of baroreflex function in rats.
authors.affiliation: Dept. of Cardiovascular Control, Kochi Medical School, Nankoku, Kochi 783-8505, Japan. tacsato-kochimed@umin.ac.jp
authors.forename: Takayuki
authors.initials: T
authors.lastname: Sato
authors.forename: Toru
authors.initials: T
authors.lastname: Kawada
authors.forename: Masashi
authors.initials: M
authors.lastname: Inagaki
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Shishido
authors.forename: Masaru
authors.initials: M
authors.lastname: Sugimachi
authors.forename: Kenji
authors.initials: K
authors.lastname: Sunagawa
mesh_terms: D000818:Animals; D017704:Baroreflex / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology*; D002344:Carotid Body / Q000502:physiology; D008297:Male; D008954:Models, Biological; D051381:Rats; D017207:Rats, Sprague-Dawley; D013564:Sympathetic Nervous System / Q000502:physiology*