Transfer function analysis of central arc of aortic baroreceptor
reflex in rabbits.
Kubo, Toshihiko, Tsutomu Imaizumi, Yasuhiko Harasawa, Shin-Ichi Ando,
Tatsuya Tagawa, Toyonari Endo, Masanari Shiramoto, and Akira
Takeshita.
Research Institute of Angiocardiology and Cardiovascular Clinic,
Faculty of Medicine, Kyushu University, Fukuoka 812-82, Japan
APStracts 2:0435H, 1995.
While electrically stimulating the aortic depressor nerve (ADN)
pseudorandomly, we recorded the responses of renal sympathetic nerve
activity (RSNA) and of systemic arterial pressure (SAP) in 19
[alpha]-chloralose anesthetized rabbits with sinoaortic denervation.
From the recorded signals, we determined the transfer functions from
ADN stimulation by a pseudorandom binary sequence to RSNA [HCMD x
RSNA(f)] and to SAP [HCMD x SAP(f)]. The modulus of HCMD x RSNA(f)
was flat over 0.0122-0.8?Hz, whereas the phase lag increased linearly
with frequency. Thus the central transduction appeared not to modify
the relative amplitude of the signals from the baroreflex afferents
but to provide a fixed time delay (400?msec). In contrast, the
modulus of HCMD x SAP(f) decreased precipitously toward high
frequencies, and the degree of the phase lag was larger than that of
HCMD x RSNA(f). We conclude that 1) the transfer property of the
central arc does not significantly modify the relative amplitude of
the frequency components of the baroreflex afferents but provides a
fixed time delay, and that 2) the frequency-independence of the
modulus of the transfer property is not preserved when the analysis
is extended to SAP. (190?words)
Received 13 December 1993; accepted in final form 31 August 1995.
APS Manuscript Number H909-3.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 November 95