Neurocardiac response to esophageal electrical stimulation in
humans: effects of varying stimulation frequencies.
Bajwa, A., S. Hollerbach, M. V. Kamath, A. R. M. Upton, D.
Fitzpatrick, E. L. Fallen, and G. Tougas.
Divisions of Gastroenterology, Cardiology and Neurological
Sciences, McMaster University Faculty of Health Sciences, Hamilton,
Ontario, Canada, L8N 3Z5
APStracts 3:0374R, 1996.
The purpose of this study was to determine if the cardioautonomic
responses to esophageal electrical stimulation were mediated entirely
through modulation of respiratory frequency or a direct vagal effect.
We performed electrical stimulation of the esophagus in 13 healthy
male controls (24 +/- 6 years) using a manometric catheter to which a
stainless steel electrode was attached. Stimulation frequencies
ranged from 0.1Hz - 1Hz and were applied in random fashion. We
computed the power spectra of the heart rate variability and
respiratory frequency as measures of autonomic function. Electrical
stimulation of the esophagus produced significant increases in the
high frequency power of the heart rate autospectrum at all
stimulation frequencies (maximal at 0.2Hz). However, regardless of
the frequency of esophageal stimulation, the respiratory rate was not
changed from baseline. These studies indicate that enhancement of
cardiac vagal modulation observed in response to esophageal
electrical stimulation, are not primarily due to changes in
respiratory frequency, but rather through a direct, vagally mediated
action through sensory neural pathways involving vagal esophageal
afferents.
Received 7 August 1996; accepted in final form 4 October 1996.
APS Manuscript Number R463-6.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 5 November 1996