Electrical activity of the intestine of mice with hereditary megacolon and absence of enteric ganglion cells.

Abstract

Mice with a recessive gene which reduces the number of ganglion cells of the large intestine and produces megacolon similar to Hirschsprung's disease were studied. Electrical activity of the small bowel consisted of electrical slow waves and action potentials and showed no difference between the mice with megacolon and their normal siblings. Electrical slow waves and action potentials occurred in the large intestine of both normal and abnormal mice. The principal difference between normal mice and their abnormal siblings was increased incidence of discharge of action potentials associated with uncoordinated phasic contractions superimposed upon tonic contracture of the circular muscle layer of the distal aganglionic segment in the abnormal mouse. The distended colon of the abnormal mouse and the entire length of the normal bowel showed bursts of action potentials which accompanied peristaltic waves of circular muscle contraction. During propulsive motility in the rectum, activation of the circular muscle was preceded by coordinated contraction of the longitudinal muscle only in the normal bowel. Symptoms of megacolon can be accounted for by the absence of spontaneously active inhibitory neurons from the enteric plexuses of the distal segment of the large bowel.