In:
American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, American Physiological Society, Vol. 277, No. 1 ( 1999-07-01), p. R140-R146
Abstract:
Recently, studies in our laboratory involving the use of a Gaussian white noise technique demonstrated that the transfer function from sympathetic stimulation frequency to heart rate (HR) response showed dynamic characteristics of a second-order low-pass filter. However, determinants for the characteristics remain to be established. We examined the effect of an increase in mean sympathetic stimulation frequency and that of a blockade of the neuronal uptake mechanism on the transfer function in anesthetized rabbits. We found that increasing mean sympathetic stimulation frequency from 1 to 4 Hz significantly ( P 〈 0.01) decreased the dynamic gain of the transfer function without affecting other parameters, such as the natural frequency, lag time, or damping coefficient. In contrast, the administration of desipramine (0.3 mg/kg iv), a neuronal uptake blocking agent, significantly ( P 〈 0.01) decreased both the dynamic gain and the natural frequency and prolonged the lag time. These results suggest that the removal rate of norepinephrine at the neuroeffector junction, rather than the amount of available norepinephrine, plays an important role in determining the low-pass filter characteristics of the HR response to sympathetic stimulation.
Type of Medium:
Online Resource
ISSN:
0363-6119
,
1522-1490
DOI:
10.1152/ajpregu.1999.277.1.R140
Language:
English
Publisher:
American Physiological Society
Publication Date:
1999
detail.hit.zdb_id:
1477297-8
SSG:
12
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