title: Short-term electroacupuncture at Zusanli resets the arterial baroreflex neural arc toward lower sympathetic nerve activity.
abstract: Although electroacupuncture reduces sympathetic nerve activity (SNA) and arterial pressure (AP), the effects of electroacupuncture on the arterial baroreflex remain to be systematically analyzed. We investigated the effects of electroacupuncture of Zusanli on the arterial baroreflex using an equilibrium diagram comprised of neural and peripheral arcs. In anesthetized, vagotomized, and aortic-denervated rabbits, we isolated carotid sinuses and changed intra-carotid sinus pressure (CSP) from 40 to 160 mmHg in increments of 20 mmHg/min while recording cardiac SNA and AP. Electroacupuncture of Zusanli was applied with a pulse duration of 5 ms and a frequency of 1 Hz. An electric current 10 times the minimal threshold current required for visible muscle twitches was used and was determined to be 4.8 +/- 0.3 mA. Electroacupuncture for 8 min decreased SNA and AP (n = 6). It shifted the neural arc (i.e., CSP-SNA relationship) to lower SNA but did not affect the peripheral arc (i.e., SNA-AP relationship) (n = 8). SNA and AP at the closed-loop operating point, determined by the intersection of the neural and peripheral arcs, decreased from 100 +/- 4 to 80 +/- 9 arbitrary units and from 108 +/- 9 to 99 +/- 8 mmHg (each P < 0.005), respectively. Peroneal denervation eliminated the shift of neural arc by electroacupuncture (n = 6). Decreasing the pulse duration to <2.5 ms eliminated the effects of SNA and AP reduction. In conclusion, short-term electroacupuncture resets the neural arc to lower SNA, which moves the operating point toward lower AP and SNA under baroreflex closed-loop conditions.
authors.affiliation: Department of Cardiovascular Dynamics, Advanced Medical Engineering Center, National Cardiovascular Center Research Institute, Suita, Osaka 565-8565, Japan. dmichi@ri.ncvc.go.jp
authors.forename: Daisaku
authors.initials: D
authors.lastname: Michikami
authors.forename: Atsunori
authors.initials: A
authors.lastname: Kamiya
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: Kenta
authors.initials: K
authors.lastname: Yamamoto
authors.forename: Hideto
authors.initials: H
authors.lastname: Ariumi
authors.forename: Satoshi
authors.initials: S
authors.lastname: Iwase
authors.forename: Junichi
authors.initials: J
authors.lastname: Sugenoya
authors.forename: Kenji
authors.initials: K
authors.lastname: Sunagawa
authors.forename: Masaru
authors.initials: M
authors.lastname: Sugimachi
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D017704:Baroreflex / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology*; D002339:Carotid Arteries / Q000294:innervation* / Q000502:physiology*; D015671:Electroacupuncture / Q000379:methods*; D005246:Feedback / Q000502:physiology; D011817:Rabbits; D013564:Sympathetic Nervous System / Q000502:physiology*