Mediators of nonadrenergic, noncholinergic relaxation in Sprague dawley rat intestine: Comparison with the mediators of other strains

Participation of nitric oxide, vasoactive intestinal peptide (VIP) and pitu itary adenylate cyclase activating peptide (PACAP) in nonadrenergic, noncho linergic (NANC) relaxation of longitudinal muscle of various intestinal reg ions in Sprague Dawley rats (8-week-old) was studied in vitro. Nitric oxide was suggested to participate in NANC relaxation of every intestinal region studied. But the participation was partial and its extent varied among the regions: significant in the proximal colon and rectum, and moderate in the jejunum, ileum and distal colon. Participation of PACAP in NANC relaxation was suggested only in the distal colon, while that of VIP was not detected in any of regions. Results obtained in the present study indicate that ext ent of participation of nitric oxide in NANC relaxation in Sprague Dawley r at intestine is more significant than those of other strains, Wistar and Wi star-ST.