AJP - Gastrointestinal and Liver Physiology, Vol 247, Issue 1 37-G42, Copyright © 1984 by American Physiological Society
Mechanisms of motility changes during acute intestinal obstruction in the dog
M. Prihoda, A. Flatt and R. W. Summers
We investigated the effects of autonomic drugs and the role of intestinal
contents on the motility changes that occur during acute obstruction.
Myoelectric activity was recorded from seven electrodes spaced at 3-cm
intervals along the midjejunum of nine conscious dogs. Another animal had
electrodes evenly placed throughout the small bowel. Obstruction was
created by inflation of an intraluminal balloon. Systemic arterial blood
pressure and pulse rate were monitored. Initially, motor activity of the
small intestine increased proximal to an acute intestinal obstruction and
decreased distally. Recordings from the entire small intestine revealed
that these effects occurred almost immediately in the region of the
obstruction but not at more distant sites. Within 2-3 h, however, proximal
hypermotility had extended to the duodenum and distal inhibition had
progressed to the terminal ileum. Diversion of intestinal contents without
obstruction reduced myoelectric activity distal to the site of drainage.
However, reinfusion of chyme distal to the site of obstruction failed to
restore inhibited motor activity to control levels. Atropine sulfate (50
micrograms/kg) decreased and neostigmine (5 micrograms X kg-1 X min-1)
potentiated the hyperactivity proximal to the obstruction, but neither
agent significantly affected the distal inhibition. Phentolamine (1 mg/kg)
and propranolol (1 mg/kg) had no effect on proximal or distal motor
activity during obstruction; these were doses that blocked cardiovascular
responses to adrenergic agonists. These results suggest that changes in
luminal contents and in nervous activity both contribute to the intestinal
motility changes that accompany obstruction.(ABSTRACT TRUNCATED AT 250
WORDS)
