AJP - Gastrointestinal and Liver Physiology, Vol 240, Issue 4 305-G311, Copyright © 1981 by American Physiological Society
Relation between electrical and mechanical activity in esophageal smooth muscle
R. K. Goyal and J. S. Gidda
Experiments were performed in anesthetized opossums. Electrical and
mechanical activity was recorded simultaneously from the esophageal body at
5, 3, and 1 cm above the lower esophageal sphincter (LES). Esophageal
responses were evoked by electrical stimulation of vagal efferents or by
induced swallowing. Electrical and mechanical activity was associated in
86% and dissociated in 14% of the 1,200 responses examined. The frequency
of dissociation was dependent on the site in the esophagus and the
frequency of vagal efferent stimulation (P less than 0.05). The interval
between the onset of electrical and mechanical events, called
electromechanical delay, had a regional gradient: 5 cm above LES greater
than 3 cm greater than 1 cm (P less than 0.01). This delay was also
dependent on the frequency of stimulation. The amplitude of spike burst and
the number of spikes in a burst closely correlated with the amplitude of
contraction. These studies show that electromechanical responses and
dissociations are dependent on the regional level in the esophagus and the
frequency of vagal stimulation.
