AJP - Gastrointestinal and Liver Physiology, Vol 258, Issue 4 519-G526, Copyright © 1990 by American Physiological Society
Myoelectric activity of small intestine after chemical ablation of myenteric neurons
G. E. Holle and W. Forth
Gastroenterological Research Laboratory, Walther Straub Institute of Pharmacology and Toxicology, Ludwig-Maximilians University, Munich, Federal Republic of Germany.
Ablation of the myenteric plexus was performed by serosal application of
0.062% benzalkonium chloride (BAC) in the duodenum, proximal and distal
jejunum, and ileum. The thickness of muscle layers and the number and sizes
of ganglia and neurons of the myenteric plexus were evaluated before and
21-28 days after treatment. Electrodes were implanted on the treated
segments and on segments orad and aborad to the treated segment. The
electromyogram of each segment was recorded daily for periods of 2-3 h. The
number of myenteric neurons in the BAC-treated segment was decreased
significantly by 85 to 98% relative to segments removed before BAC
application. Significantly, thickening of longitudinal plus circular muscle
layers amounted to 113% in the duodenum and 261% in the ileum in the
treated segment. No changes were observed in electrical slow-wave frequency
in treated segments. Spike activity (percentage of slow waves with spikes)
increased in the BAC-treated segment by 92% compared with recording sites
orad and aborad to the treated segment and to the small intestine in
untreated control animals. We interpreted the increase in spike activity in
treated segments to reflect the loss of inhibitory neuronal influence. The
hyperplasia and hypertrophy of the longitudinal and circular muscle coat
could have resulted from a direct influence of the altered innervation or
from work-induced hypertrophy in the treated segment secondary to
uncoordinated hyperactivity of the disinhibited musculature.
