| Abstract: | This experiment was designed to determinemechanisms of change in nonadrenergic, noncholinergic(NANC) inhibitory neurons in the ileum after small boweltransplantation (SBT) in the rat and whether nitric oxide (NO) serves as an important NANCinhibitory neurotransmitter in the rat ileum. Eightgroups of rats (N  8 rats/group) were studied:neurally intact unoperated controls; rats one week afteranesthesia and sham celiotomy; and separate groups one andeight weeks after either 40 min of cold ischemia of thejejunoileum, combined jejunal and ileal intestinaltransection/reanastomosis, or orthotopic SBT of the entire jejunoileum. Contractile activitywas evaluated in full-thickness ileal circular musclestrips under isometric conditions. Spontaneous activitydid not differ among groups. In all groups, exogenous NO, NG-monomethyl-L-arginine(L-NMMA, an NO synthase inhibitor), and methylene blue(soluble guanylate cyclase inhibitor) had no effect onspontaneous activity, while 8-bromocyclic guanosinemonophosphate (8Br-cGMP) inhibited contractile activity inall groups. Low frequency (2-10 Hz) electrical fieldstimulation (EFS) inhibited contractile activity only incontrol and SBT groups; L-NMMA and methylene blue did not alter the response to EFS in any group.These results suggest that each aspect of the SBTprocedure, ischemia/reperfusion injury, disruption ofenteric neural continuity by intestinal transection, and extrinsic denervation, alter function ofenteric ileal inhibitory neurons separately early (oneweek) after operation. NO, a known inhibitoryneurotransmitter in other gut regions, does not affectileal circular muscle in neurally intact tissue normediate functional changes in inhibitory nerve functionnor smooth muscle contractility after SBT. |
