Myoelectrical Activity in Experimental Aganglionosis of the Colon in the Rat

Abstract

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.

Effect of ganglionic stimulating and blocking agents on the fast components of colonic myoelectrical activity in the rat

“…The myoelecepicd activity showed two fast components with frequencies of 4-7 cps ( W A ) and 25-40 cps (FA), as reported earlier ( S h m a et al 198 1; Chandran et al 1982). The inflation of the bdloon increased the frequency of MFA from 5.0 5 0.82 cps (range 4-6) to 8.75 k % .26 cps (7-lo), without affecting the FA (Fig.…”

“…Disruption of such a neuronal mechanism, as in ganglionic blockade, may produce the aganglionic pattern lacking MFA. The present study also shows that the cholinergic transmission is the most important factor for this neuronal integration of myoelectrical activity, since the cholinergie ganglionic blockade in the present study produced an EMG pattern completely devoid of MFA, a pattern we had reported in Hirschspmng's disease and in experimental aganglionosis (Chandran et al 1982;M q a et al 1986; S h m a et al 198 1).…”

“…The SWA was recorded separately at slow speed (1 mm/s) and a higher time constant (0.5 s). Two types of fast activities were recorded, FA with a frequency of 25-40 cps superimposed over MFA with a frequency of 4-7cps (Chandran et al 1982;S h m a et al 1981). In Hirschspmng's disease and in experimental aganglionosis of colon in the rat, the EMG from the aganglionic segments chaacteristically showed an absence of MFA (Chmdran et al 1982;Maya et al 1986;S h m a et al 1981).…”

“…The MFA was found to be absent in Hirschspmng's disease a d this criterion has been successfully used in the diagnosis of Hirschspmng 's disease ( M w a et al 1986). Experimentally produced aganglionosis of colon in the rat also showed an absence of MFA (Chandran et al 1982). These studies suggest that the enteric ganglia are responsible for the genesis of 'Author to whom correspondence may be sent at the following address: 25/9 J, Medical Enclave, Rohtak 124 001, India.…”

Are interstitial cells of Cajal plurifunction cells in the gut?

“…Although the target of these mutations are the precursor cells of the enteric neurons, these models also exhibit abnormalities of structure and function in the surrounding cells, such as the smooth muscle cells (166). Slow waves are absent in the circular smooth muscle cells of the aganglionic segment in patients with Hirschsprung's disease (89) and in mutant rodent models of aganglionosis, even though the enteric neurons are not involved in the generation of slow waves in wild-type animals (25,90). The cytoskeleton proteins are also markedly reduced in the smooth muscle cells of the aganglionic bowel in Hirschsprung's disease (109).…”