NITRIC OXIDE-RELATED NEURAL COMPONENTS IN THE RAT SMALL-INTESTINE AFTER TRANSPLANTATION

The changes in nitric oxide (NO)-related neural components in the tran splanted small intestine are unknown. In this study, the NO neural com ponent was examined using electrophysiological and NADPH-diaphorase hi stochemical techniques in a rat small bowel transplantation model. Syn geneic total small bowel transplantation was performed in 26 male Lewi s rats using microsurgical techniques. The rats were divided into four groups: an untreated control group and animals at 1 (G1), 2 (G2), and 4 (G4) weeks after transplantation. Jejunal strips were mounted in a superfusion apparatus for examination. In the presence of atropine and guanethidine, the effect of the NO synthesis inhibitor LN(G)-nitro-ar ginine (L-NNA, 100 mu M) relaxation mediated by the nonadrenergic, non cholinergic (NANC) neural system was assessed following electrical sti mulation at 2 Hz. The inhibitory effect of L-NNA on relaxation was tak en as an indicator of NO production. The percentage of inhibition in t he control group, and in G1, G2, and G4 was 43.30 % +/- 6.08 % (mean /- SE), 42.10 % +/- 6.69 %, 43.62 +/- 10.90 %, and 52.46 % +/- 6.00 %, respectively. Inhibition in G4 was significantly higher than in the o ther groups (P < 0.01). The percentage of NADPH-diaphorase-positive fi bers in the control group, G1, G2, and G4 was 25.06 % +/- 4.70 % (mean + SE), 26.27 % +/- 2.17 %, 24.73 % +/- 2.87 %, and 30.76 % +/- 3.19 % , respectively. Again, G4 showed a significantly higher level than the other groups (P < 0.01). We conclude that increased NO production may play a significant role in maintaining the intrinsic nervous system o f the small intestine after transplantation.