NITRIC-OXIDE SYNTHASE IMMUNOREACTIVITY IN THE HUMAN ILEOCECAL REGION

The nitric oxide (NO) producing neurons in the human ileocecal region (pre-junctional ileum, ileocecal and cecocolonic junctions, cecum and post-junctional colon) have been evaluated by immunocytochemistry. The percentage of NO synthase-positive neurons was higher at the myenteri c plexus than at the submucous plexus, independently of the levels exa mined. The inner portion of the circular muscle layer, except at the i leal level, was devoid of immunoreactive nerve fibers. Data obtained s uggest that neuronal-released NO at the ileocecal region has a greater role in the relaxation of the muscle coat, except for the inner circu lar muscle layer, than in the regulation of blood flow, absorptive and secretory processes.