Neurotensin, neuromedin N and xenopsin induced a monophasic and concentration-dependent contraction of the intact guinea pig oesophagus but kinetensin was without effect. The responses were completely abolished by tetrodoxin and atropine but were unaffected by hexamethonium. The maximum response induced by neurotensin was reduced (20-30%) by somatostatin and by dynorphin-(1-13) in a naloxone-reversible manner. Neurotensin did not contract the isolated muscularis mucosae. The effects of neurotensin-related peptides on the motility of the oesophagus are mediated exclusively through the release of acetylcholine.
- Neuromedin N
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