Search results for "NK1 receptor"
showing 5 items of 5 documents
Role for NK1 and NK2 receptors in the motor activity in mouse colon
2007
The present study examined the effects induced by endogenous and exogenous activation of NK(1) and NK(2) receptors on the mechanical activity of mouse proximal colon. Experiments were performed in vitro recording the changes in intraluminal pressure from isolated colonic segments. Electrical field stimulation in the presence of atropine and guanethidine produced a small relaxation, followed by nonadrenergic noncholinergic (NANC) contraction. SR140333, NK(1) receptor antagonist, or SR48968, NK(2) receptor antagonist, significantly reduced the contraction, although SR48968 appeared more efficacious. The co-administration of SR140333 and SR48968 virtually abolished the NANC contraction. [Sar(9…
Altered tachykinergic influence on gastric mechanical activity in mdx mice
2006
Abstract This study investigated whether alterationsin gastric activity in dystrophic mdx mouse can beattributed to dysfunctions of tachykinins. Endolumi-nal pressure was recorded and the expression ofneuronal nitric oxide synthase (nNOS), NK1 and NK2neurokinin receptors was investigated by immunoh-istochemistry. SR48968, NK2 receptor antagonist, butnot SR140333, NK1 receptor antagonist, decreased thetone only in mdx gastric preparations. In the presenceof N x -nitro- L -arginine methyl ester ( L -NAME), inhib-itor of NOS, SR48968 reduced the tone also in normalstomach. [Sar 9 , Met(O 2 ) 11 ]-SP, agonist of NK1 recep-tors, caused tetrodotoxin-sensitive relaxations, antag-onized by SR140333…
NK1- and NK3-receptor mediated inhibition of 5-hydroxytryptamine release from the vascularly perfused small intestine of the guinea-pig
1997
The effects of tachykinins on the spontaneous release of 5-hydroxytryptamine (5-HT) from the enterochromaffin cells into the portal circulation was investigated in vitro using the vascularly perfused isolated guinea-pig small intestine. 5-HT was determined by HPLC with electrochemical detection. Test substances were applied intraarterially. Substance P (SP) caused a concentration-dependent decrease in 5-HT outflow with an EC50 of 50 pmol/l. Similarly, the selective NK1 receptor agonist SP methyl ester (1 nmol/l) significantly inhibited 5-HT outflow (to 51 +/- 3%). When tetrodotoxin (1 mumol/l) was added to the arterial perfusion medium, the inhibition by SP of 5-HT outflow was not affected.…
Role of NK1 and NK2 receptors in mouse gastric mechanical activity
2006
The aim of the present study was to examine the role of NK1 and NK2 receptors in the control of mechanical activity of mouse stomach. In this view, the motor effects induced by NK1 and NK2 receptor agonists and antagonists were analyzed, measuring motility as intraluminal pressure changes in mouse-isolated stomach preparations. In parallel, immunohistochemical studies were performed to identify the location of NK1 and NK2 receptors on myenteric neurons and smooth muscle cells. Substance P (SP) induced biphasic effects: a contraction followed by relaxation; neurokinin A (NKA) and [β-Ala8]-NKA(4−10), selective agonist of NK2 receptors, evoked concentration-dependent contractions, whereas [Sar…
Involvement of nitric oxide and tachykinins in the effects induced by protease-activated receptors in rat colon longitudinal muscle
2003
The aim of the present study was to verify a possible involvement of nitric oxide (NO) and of tachykinins in the contractile and relaxant effects caused by the activation of protease-activated receptor (PAR)-1 and PAR-2 in the longitudinal muscle of rat colon. Mechanical responses to the PAR-1 activating peptides, SFLLRN-NH2 (10 nM–10 μM) and TFLLR-NH2 (10 nM–10 μM), and to the PAR-2-activating peptide, SLIGRL-NH2 (10 nM–10 μM), were examined in vitro in the absence and in the presence of different antagonists. The relaxation induced by SFLLRN-NH2, TFLLR-NH2 and SLIGRL-NH2 was antagonised by the inhibitor of NO synthase L-Nω-nitroarginine methyl ester (300 μM), or by the inhibitor of the gu…