Evidence that sensory neurons participate in the non-cholinergic, non-adrenergic contractile response of the guinea-pig ileum.
The possible role of non-cholinergic, non-adrenergic (NCNA) nerves in responses of the guinea-pig terminal ileum to transmural nerve stimulation (TNS) and that of sensory nerves in NCNA responses were investigated. The action of acetylcholine was almost abolished in the presence of histamine, whereas the contractions elicited by TNS were changed to frequency-dependent contraction followed by a secondary relaxation. Guanethidine did not alter the contractions or secondary relaxations. Atropine abolished the action of acetylcholine and transiently suppressed the responses to low (up to 2 Hz) and attenuated (by about 50%) those to high (4 to 20 Hz) frequency stimulation. The remaining complex NCNA response was the sum of the excitatory and inhibitory responses. During desensitization to capsaicin, and in its presence, the NCNA contractions were reduced, whereas the relaxations were not significantly enlarged. The present results suggest that besides the cholinergic innervation, the excitatory and inhibitory NCNA innervation also participates in the responses of the guinea-pig ileum to TNS even without suppression of cholinergic and adrenergic transmission, and that the sensory nerves are, at least to some extent, involved in the NCNA excitatory response.
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Matusák
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Bauer
D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002211:Capsaicin / Q000494:pharmacology; D004558:Electric Stimulation; D006145:Guanethidine / Q000494:pharmacology; D006168:Guinea Pigs; D006632:Histamine / Q000494:pharmacology; D007082:Ileum / Q000187:drug effects / Q000294:innervation*; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009126:Muscle Relaxation / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology*; D009475:Neurons, Afferent / Q000502:physiology*; D013373:Substance P / Q000502:physiology*
D013373:Substance P; D001285:Atropine; D006632:Histamine; D002211:Capsaicin; D006145:Guanethidine