Auto- and cross-spectral analysis of cardiovascular fluctuations
during pentobarbital anesthesia in the rat.
Yang, Cheryl C. H., Terry B. J. Kuo, and Samuel H. H. Chan.
Center for Neuroscience, National Yang-Ming University, Taipei
11221, Taiwan, Republic of China
APStracts 2:0358H, 1995.
We applied auto- and cross-spectral analysis of systemic arterial
pressure (SAP) and heart rate (HR) signals to quantify the effects of
pentobarbital sodium on short-term cardiovascular fluctuations in
adult, male Sprague-Dawley rats. Intravenous administration of
pentobarbital, delivered as a bolus injection (5, 10 or 20 mg/kg) or
continuous infusion (10, 20 or 40 mg.kg-1.h-1), elicited only mild
hypotension and tachycardia. This was accompanied by a dose-related
depression of the very low (0-0.25 Hz) and low (0.25-0.8 Hz)
frequency components of both SAP and HR, and high (0.8-2.4 Hz)
frequency component of HR, signals. Cross-spectral analysis of SAP
and HR signals during iv infusion of pentobarbital revealed a
maintained coherence in the high frequency range, together with a
gradual and dose-related decrease in magnitude of transfer function
and barore ceptor reflex sensitivity. Stable plasma concentration and
all hemodynamic parameters were observed during 120 min of infusion
at 20 mg.kg-1.h-1. Under this dosing condition, autonomic blockade by
phentolamine, pro pranolol or atropine still evoked discernible but
differential reduction in the SAP and HR spectral components. Our
data suggest that continuous iv administration of pentobarbital at 20
mg.kg-1.h-1 offers maintained anes thesia while preserving the
capacity of cardiovascular regulation.
Received 16 February 1995; accepted in final form 2 August 1995.
APS Manuscript Number H146-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 24 August 1995.