1. The role of NK1 and NK3 receptors in synaptic transmission between myenteric neurons during motility reflexes in the @entity840 ileum was investigated by recording intracellularly the reflex responses of the circular muscle to distension or @entity2850 . Experiments were performed in a three-chambered organ bath that enabled drugs to be selectively applied to different sites along the reflex pathways. 2. When applied in the recording chamber, an @entity13630 antagonist, @entity13631 (100 nM), reduced by 40-50% the amplitudes of inhibitory junction potentials (i.j.ps) evoked in the circular muscle by activation of descending reflex pathways. This effect was abolished when synaptic transmission in the stimulus region was blocked with physiological saline containing 0.1 mM @entity141 plus 10 mM @entity1025 , leaving only the component of the descending reflex pathway conducted via long anally directed collaterals of intrinsic sensory neurons. 3. @entity13631 (100 nM) had no effect on descending reflex i.j.ps when applied to the stimulus region. Ascending reflexes were also unaffected by @entity13631 in the stimulus region or between the stimulus and recording sites. 4. Septide (10 nM), an @entity13630 agonist, enhanced descending reflexes by 30-60% when in the recording chamber. [Sar9,Met(O2)11]substance P had no effect at 10 nM, but potentiated distension-evoked reflexes at 100 nM. 5. A selective @entity21385 antagonist, @entity21386 (100 nM), when applied to the stimulus region, reduced the amplitude of descending reflex responses to compression by 40%, but had no effect on responses to distension. @entity21386 (100 nM) had no effect when applied to other regions of the descending reflex pathways. 6. @entity21386 (100 nM) only inhibited ascending reflexes when applied at the recording site. However, after nicotinic transmission in the stimulus region was blocked, @entity21386 (100 nM) at this site reduced responses to compression. 7. Contractions of the circular muscle of isolated rings of ileum evoked by low concentrations of septide, but not [Sar9,Met(O2)11]substance P, were potentiated by tetrodotoxin (300 nM). 8. Contractile responses evoked by an @entity21385 agonist, senktide, were non-competitively inhibited by @entity21386 . After excitatory neuromuscular transmission was blocked, senktide produced inhibitory responses that were also antagonised by @entity21386 , but to a lesser extent and in an apparently competitive manner. 9. These results indicate that @entity4756 acting via NK1 receptors partly mediate transmission to inhibitory motor neurons. NK3 receptors play a role in transmission from intrinsic sensory neurons and from ascending interneurons to excitatory motor neurons during motility reflexes.

Roles of neuronal NK1 and NK3 receptors in synaptic transmission during motility reflexes in the XXXX ileum.

@entity21385 :: ('100135627(Tax:10141)', 'Gene') :: ['NK3 receptor'] @entity1025 :: ('CHEBI:18420', 'Chemical') :: ['Mg2+'] @entity13630 :: ('100135626(Tax:10141)', 'Gene') :: ['NK1 receptor'] @entity13631 :: ('MESH:C085215', 'Chemical') :: ['SR140333'] @entity840 :: ('10141', 'Species') :: ['guinea-pig'] @entity2850 :: ('MESH:D009408', 'Disease') :: ['compression of the mucosal villi'] @entity21386 :: ('MESH:C091554', 'Chemical') :: ['SR142801'] @entity141 :: ('CHEBI:29108', 'Chemical') :: ['Ca2+'] @entity4756 :: ('MESH:D015320', 'Chemical') :: ['tachykinins']
@entity840 :: (10141,Species) :: ['guinea-pig']
