title: Afferent vagal nerve stimulation resets baroreflex neural arc and inhibits sympathetic nerve activity.
abstract: It has been established that vagal nerve stimulation (VNS) benefits patients and/or animals with heart failure. However, the impact of VNS on sympathetic nerve activity (SNA) remains unknown. In this study, we investigated how vagal afferent stimulation (AVNS) impacts baroreflex control of SNA. In 12 anesthetized Sprague-Dawley rats, we controlled the pressure in isolated bilateral carotid sinuses (CSP), and measured splanchnic SNA and arterial pressure (AP). Under a constant CSP, increasing the voltage of AVNS dose dependently decreased SNA and AP. The averaged maximal inhibition of SNA was -28.0 ± 10.3%. To evaluate the dynamic impacts of AVNS on SNA, we performed random AVNS using binary white noise sequences, and identified the transfer function from AVNS to SNA and that from SNA to AP. We also identified transfer functions of the native baroreflex from CSP to SNA (neural arc) and from SNA to AP (peripheral arc). The transfer function from AVNS to SNA strikingly resembled the baroreflex neural arc and the transfer functions of SNA to AP were indistinguishable whether we perturbed ANVS or CSP, indicating that they likely share common central and peripheral neural mechanisms. To examine the impact of AVNS on baroreflex, we changed CSP stepwise and measured SNA and AP responses with or without AVNS. AVNS resets the sigmoidal neural arc downward, but did not affect the linear peripheral arc. In conclusion, AVNS resets the baroreflex neural arc and induces sympathoinhibition in the same manner as the control of SNA and AP by the native baroreflex.
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 Advanced Therapeutics for Cardiovascular Diseases, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Kishi
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: 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: Takafumi
authors.initials: T
authors.lastname: Sakamoto
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: 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: Masataka
authors.initials: M
authors.lastname: Ikeda
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
keywords: Afferent nerve; carotid sinus baroreflex; sympathetic nerve activity; vagal nerve stimulation