Myoelectrical activity in experimental aganglionosis of the colon in the rat.

Experimental aganglionosis of the colon was produced in rats by an experimental "aganglionosis producing" procedure. Radiological examination of the aganglionic colon showed a narrow segment distal to a dilated megacolon. Histologically, a transverse section of the aganglionic segment showed 3-4 ganglia in contrast to 32-40 ganglia per section in the normal colon. The myoelectrical activity of the normal colon presented two fast activities, a fast activity with a frequency of 25-40 cycles per sec superimposed over a medium-fast activity of 4-7 cycles per sec. However the aganglionic colon showed only the fast activity with complete absence of the medium-fast activity. Thus the experimental aganglionosis produced a characteristic alteration in the myoelectrical activity of colon. This confirms our earlier findings in children with Hirschsprung's disease. It also suggests that the causative mechanism for the production of a narrow segment in Hirschsprung's disease may not be the hyperactivity or the absence of any specific neuronal mechanisms as proposed earlier.