Premium
Nitric oxide modulates cholinergic reflex pathways to the longitudinal and circular muscle in the isolated guinea‐pig distal colon
Author(s) -
Smith Terence K.,
McCarron Sarah L.
Publication year - 1998
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1111/j.1469-7793.1998.893bd.x
Subject(s) - stimulation , contraction (grammar) , nitric oxide , chemistry , snap , reflex , guinea pig , muscle contraction , acetylcholine , anatomy , cholinergic , endocrinology , medicine , computer graphics (images) , computer science
1 The involvement of nitric oxide (NO) in enteric neural pathways underlying reflex responses of the longitudinal muscle (LM) and circular muscle (CM) layers activated by mucosal stimulation was examined in the isolated guinea‐pig distal colon. 2 A segment of colon spanned two partitions (10 mm apart), which divided the organ bath into three chambers: a recording chamber where LM and CM tension was measured; a stimulation chamber where mucosal stimulation was applied; and a middle chamber separating them. 3 Brushing the mucosa anal and oral to the recording site evoked simultaneous oral contraction and anal relaxation of both the LM and CM. 4 Nω ‐nitro‐L‐argininel‐NA; 100 μ m ) or N ω ‐nitro‐L‐arginine methyl ester ( l ‐NAME; 100 μ m ) applied to the middle chamber or stimulation chamber decreased the oral contractile response of the LM and CM (by about 30–40 %), but increased the anal relaxation (> 600 %) and exposed an anal contraction (> 1000 % increase) of both muscles. The addition of l ‐NA to the recording chamber reduced the anal relaxation of the LM and CM and the anal contraction of the LM, but slightly increased the anal contraction of the CM. 5 S ‐Nitroso‐ N ‐acetylpenicillamine (SNAP; 10 μ m ), an NO donor, reversed the effects of l ‐NA in the middle or stimulation chambers. 6 1 H ‐[1,2,4]oxadiazolo[4,3‐a]quinoxalin‐1‐one (ODQ; 10 μ m ), a soluble guanylate cyclase inhibitor, mimicked the effects of l ‐NAin the middle chamber or stimulation chamber, but these effects were not reversed by SNAP. 7 The oral contractile responses, and the anal relaxation and contractile responses of the LM and CM produced by l ‐NA in the stimulation or middle chambers, were blocked by hexamethonium (300 μ m ) in any chamber. Atropine (1 μ m ) in the recording chamber reduced the contractile responses of the LM and CM. 8 In conclusion, endogenous NO facilitates and depresses release of acetylcholine from interneurons in ascending and descending nervous pathways, respectively. These NO effects are mediated through soluble guanylate cyclase in cholinergic interneurons