Chronic extrinsic denervation of the small bowel: effect on adrenergic and cholinergic contractile mechanisms in canine ileal circular muscle.
BACKGROUND
Small bowel transplantation necessitates chronic extrinsic denervation and is often followed by enteric dysfunction. Our aim was to study canine ileal contractile activity after extrinsic denervation.


METHODS
In vitro dose responses to cholinergic and adrenergic agonists were evaluated in canine ileal muscle strips in control subjects and after jejunoileal extrinsic denervation (EX DEN) at 0, 2, and 8 weeks after operative preparation.


RESULTS
Spontaneous activity and the increased activity after tetrodotoxin (enteric nerve blockade) did not differ between groups. Response to acetylcholine and bethanechol did not differ at any time in the control or EX DEN group. In contrast, the EX DEN group demonstrated a procontractile hypersensitivity to norepinephrine at 2 and 8 weeks that was not seen in the control group. This adrenergic hypersensitivity in the EX DEN group was insensitive to intramural neural blockade with tetrodotoxin.


CONCLUSIONS
Extrinsic denervation does not affect basal contractile activity, augmented contractile activity to intramural neural blockade, nor response to cholinergic agonists. However, it induces a procontractile adrenergic hypersensitivity in canine ileal circular muscle mediated at the level of the smooth muscle and not at the enteric nervous system.
Balsiger
Bruno M
BM
Gastroenterology Unit, Inselspital, University of Bern, 3010 Bern, Switzerland.
Sarr
Michael G
MG
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D018723:Bethanechol / Q000494:pharmacology; D003714:Denervation; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D005260:Female; D007082:Ileum / Q000294:innervation* / Q000502:physiology*; D066298:In Vitro Techniques; D007583:Jejunum / Q000294:innervation*; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000502:physiology*; D009638:Norepinephrine / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology
D018723:Bethanechol; D013779:Tetrodotoxin; D000109:Acetylcholine; D009638:Norepinephrine