RESUMEN
The present study was planned to evaluate role of tachykinins (TKs) and neurokinin (NK) receptors in the regulation of gastric motility in sheep. We examined the effects of intravenous (i.v.) injection of neurokinin A (NKA) and substance P (SP) on motility of the rumen, omasum, and abomasum in conscious sheep and the effects of NK receptor blockade on the effect of TKs using NK-1 receptor antagonist L-732,138 and NK-2 receptor antagonist SR48968. Moreover, the effect of NK receptor blockade on omasal cyclic contractions was examined. Intravenous injection of NKA and SP induced tonic contraction of rumen, omasum, and abomasum, and the contractile effect of NKA was more potent than that of SP in all the gastric regions. Although the effect of SP was not inhibited by L-732,138, the effect of NKA was significantly inhibited by SR48968. However, single infusion of SR48968 and L-732,138 did not alter cyclic electromyographic activity and basal intraluminal pressure in the omasum. These results imply that NKA and NK-2 receptors play a primary role in non-cholinergic regulation of ovine gastric motility, though NK-2 and NK-1 receptors seem unlikely to be involved in the physiological regulation of omasal cyclic contractions.
Asunto(s)
Abomaso/efectos de los fármacos , Motilidad Gastrointestinal/efectos de los fármacos , Receptores de Neuroquinina-2/fisiología , Rumen/efectos de los fármacos , Taquicininas/fisiología , Animales , Benzamidas/farmacología , Inyecciones Intravenosas , Cinética , Masculino , Contracción Muscular/fisiología , Neuroquinina A/administración & dosificación , Neuroquinina A/farmacología , Omaso/efectos de los fármacos , Piperidinas/farmacología , Receptores de Neuroquinina-2/antagonistas & inhibidores , Receptores de Neuroquinina-2/efectos de los fármacos , Ovinos , Sustancia P/farmacología , Triptófano/análogos & derivados , Triptófano/farmacologíaRESUMEN
The present study investigated a role of tachykinins (TK) and neurokinin (NK) receptors (NK-R) in the non-cholinergic regulation of omasal contractions in sheep. Semiquantitative reverse transcription (RT)-PCR revealed that both preprotachykinin (PPT)-A and PPT-B mRNA were distributed in the omasal muscle layers and that NK-R type-1 (NK-1R) and type-2 (NK-2R) mRNA were largely expressed in the same tissues. Cumulative application of substance P (SP), neurokinin A (NKA), and neurokinin B (NKB) at 0.03-10µM induced tonic contractions of omasal muscle strips, and the contractile amplitude increased in order of NKBAsunto(s)
Contracción Muscular
, Omaso/fisiología
, Precursores de Proteínas/fisiología
, Receptores de Neuroquinina-1/metabolismo
, Receptores de Neuroquinina-2/metabolismo
, Taquicininas/fisiología
, Animales
, Atropina/farmacología
, Estimulación Eléctrica
, Expresión Génica
, Técnicas In Vitro
, Indoles/farmacología
, Masculino
, Contracción Muscular/efectos de los fármacos
, Músculo Liso/efectos de los fármacos
, Músculo Liso/metabolismo
, Músculo Liso/fisiología
, Antagonistas del Receptor de Neuroquinina-1
, Omaso/efectos de los fármacos
, Omaso/metabolismo
, Especificidad de Órganos
, Piperidinas/farmacología
, Precursores de Proteínas/metabolismo
, Precursores de Proteínas/farmacología
, Receptores de Neuroquinina-1/agonistas
, Receptores de Neuroquinina-1/genética
, Receptores de Neuroquinina-2/agonistas
, Receptores de Neuroquinina-2/antagonistas & inhibidores
, Receptores de Neuroquinina-2/genética
, Ovinos
, Taquicininas/metabolismo
, Taquicininas/farmacología
, Triptófano/análogos & derivados
, Triptófano/farmacología