Bi-directional augmentation of heart rate regulation by the
autonomic nervous system in rabbits.
Kawada, Toru, Yasuhiro Ikeda, Masaru Sugimachi, Toshiaki Shishido,
Osamu Kawaguchi, Toji Yamazaki, Joe Alexander, Jr., Kenji Sunagawa.
Institution: Department of Cardiovascular Dynamics and Department
of Cardiac Physiology, The National Cardiovascular Center Research
Institute, Japan and Department of Biomedical Engineering, Vanderbilt
University, Nashville, Tennessee, USA
APStracts 3:0049H, 1996.
Although the characteristics of the static interaction between the
sympathetic and parasympathetic nervous systems in regulating heart
rate have been well established, how the dynamic interaction
modulates the heart rate response remains unknown. Therefore, we
investigated dynamic interaction by estimating the transfer function
from nerve stimulation to heart rate using a band-limited Gaussian
white noise technique. The transfer function relating dynamic
sympathetic stimulation to heart rate had characteristics of a second
order low-pass filter. Simultaneous tonic vagal stimulation at 5 and
10 Hz increased gain of the transfer function by 55.0 ( 40.1 and 80.7
( 50.5%, respectively (p<0.05). The transfer function from
dynamic vagal stimulation to heart rate had characteristics of a
first order low-pass filter. Simultaneous tonic sympathetic
stimulation at 5 and 10 Hz increased the gain by 18.2 ( 17.9 and 24.1
( 18.0%, respectively (p<0.05). Thus, interaction augmented
dynamic gain bidirectionally even though it affected mean heart rate
antagonistically. By virtue of this interaction, the autonomic
nervous system appears to extend its dynamic range of operation.
Received 17 August 1995; accepted in final form 18 January 1996.
APS Manuscript Number H780-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 8 February 96