The neural arc of the baroreflex optimizes dynamic arterial
pressure regulation in achieving both stability and quickness.
Ikeda, Yasuhiro, Toru Kawada, Masaru Sugimachi, Osamu Kawaguchi,
Toshiaki Shishido, Takayuki Sato, Hiroshi Miyano, Wataru Matsuura,
Joe Alexander, Jr., and Kenji Sunagawa.
Department of Cardiovascular Dynamics, National Cardiovascular
Center Research Institute, 5-7-1 Fujishirodai, Suita, Osaka 565,
JAPAN, Department of Biomedical Engineering, Vanderbilt University,
Nashville, Tennessee 37235
APStracts 3:0091H, 1996.
The baroreflex loop consists of both a fast neural arc and a slow
mechanical arc. We hypothesized that the neural baroreflex arc
compensates the slow mechanical response and thus improves the
quality of blood pressure regulation. We estimated the open-loop
transfer characteristics of the neural baroreflex arc?(Hn), that is,
from carotid sinus pressure to sympathetic nerve activity (SNA), and
that of the effective peripheral baroreflex arc?(Hp), from SNA to
arterial pressure in anesthetized rabbits. The gain of Hn was
constant below 0.12?+/-?0.057?Hz and increased with a slope of
6.1?_?0.06?dB/octave above its frequency up to 1 Hz. In contrast, the
gain of Hp was constant below 0.071?+/-?0.03 Hz and decreased with a
slope of -11.0 ?_? 1.48 dB/octave above the frequency. These data
indicate that Hn accelerates slow peripheral responses in the
frequency range of 0.1-1?Hz. Although too much acceleration in the
high frequency range could result in instability of the system,
numerical analysis of the closed-loop baroreflex response indicated
that the neural arc optimized arterial pressure regulation in
achieving both stability and quickness.
Received 24 July 1995; accepted in final form 22 February 1996.
APS Manuscript Number H701-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 13 March 96