Mechanical stimulation is not responsible for activation of
gastrointestinal afferents during ischemia.
Pan, Hui-Lin, Zachary B. Zeisse, and John C. Longhurst.
Division of Cardiovascular Medicine, Departments of Internal
Medicine and Human Physiology University of California School of
Medicine, Davis, California 95616
APStracts 3:0304H, 1996.
Abdominal ischemia reflexly excites the cardiovascular system through
activation of visceral sympathetic afferents. Although a number of
ischemic metabolites are known to stimulate sympathetic afferents,
the contribution of mechanical stimulation to activation of afferents
during abdominal ischemia remains uncertain. Thus, the present study
examined the role of changes in motility in activation of
gastrointestinal afferents during ischemia. Single-unit activity of
C-fiber afferents located on the stomach, duodenum, jejunum, or colon
was recorded from the right sympathetic chain of anesthetized cats
during 15 min of ischemia. Intraluminal pressure, as a reflection of
local mechanical activity, was measured by an open catheter placed in
the lumen of the gastrointestinal tract. The results show that
gastrointestinal motility was mainly inhibited during abdominal
ischemia. Changes in intraluminal pressure did not correlate with
afferent discharge activity during ischemia (r=-0.32, n=10).
Furthermore, discharge frequency of gastrointestinal afferents during
ischemia was not altered significantly by topical application of 100
[mu]g/ml of atropine (3.98+/-0.62 to 3.83+/-0.59 imp/sec, n=12),
which profoundly inhibited local gastrointestinal motility.
Collectively, these data indicate that gastrointestinal motility
changes during abdominal ischemia do not contribute to activation of
gastrointestinal sympathetic C-fiber afferents.
Received 22 January 1996; accepted in final form 21 June 1996.
APS Manuscript Number H59-6.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 25 July 1996