Role of nitric oxide in the left-sided colon of patients with diverticulardisease

nerves in the enteric nervous system of the human gut. Recently, it has bee n established that nitric oxide is released by stimulation of non-adrenergi c non-cholinergic inhibitory nerves. Therefore, in order to evaluate the fu nction of nitric oxide in the left-sided colon of patients with diverticula r disease, we examined the enteric nerve responses in colonic tissues from patients with this disease, and also used the left-sided normal colon as a control. Methodology: Colonic tissue specimens (the diverticular bearing segments) w ere obtained from 9 patients with diverticular disease of the left-sided co lon, and normal segments of the left-sided colon were obtained from 16 pati ents with ascending colon cancer. A mechanograph was used to evaluate in vi tro colonic responses to electrical field stimulation of adrenergic and cho linergic nerve before and after treatments with various autonomic nerve Non -adrenergic non-cholinergic inhibitory nerves are the most important blocke rs, NG-nitro-L-arginine, and L-arginine. Results: 1) The diverticular colon was more strongly innervated by choliner gic nerves than the normal colon (P<0.01); 2) Non-adrenergic non-cholinergi c inhibitory nerves were found to act on the normal colon and to a lesser e xtent in the diverticular colon (P<0.05). 3) Nitric oxide mediates the rela xation reaction of non-adrenergic non-cholinergic inhibitory nerves in the normal colon and to a lesser extent in the diverticular colon. Conclusions: These findings suggest that the intrinsic intestinal innervati on contains excitatory and inhibitory nerves and that the former, especiall y cholinergic nerves, are dominant in the left-sided colon with diverticula . In addition, diminution of action of non-adrenergic non-cholinergic inhib itory nerves by substances such as nitric oxide may be largely related to t he high intraluminal pressure by colonic segmentation observed in the left- sided colon with diverticula.