Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P20366 (substance P)
 21,176 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Glucocorticoids inhibit plasma extravasation induced in the rat tracheal mucosa by substance P and other tachykinins released from sensory nerves. This study was performed to determine whether this antiinflammatory effect of glucocorticoids is mediated by the tachykinin-degrading enzymes neutral endopeptidase (NEP) and kininase II (angiotensin converting enzyme, ACE). In addition, we studied the effect of dexamethasone on a nonpeptide inflammatory mediator, platelet-activating factor (PAF), which is not degraded by NEP or ACE. Adult male pathogen-free F344 rats were treated for 2 d with dexamethasone (0.5 mg/kg per d i.p.), or with the vehicle used to dissolve the steroid. The magnitude of plasma extravasation produced by an intravenous injection of substance P (5 micrograms/kg) or PAF (10 micrograms/kg) was then assessed by using Monastral blue pigment as an intravascular tracer. The role of NEP and ACE activities in the changes produced by dexamethasone was investigated by examining the effect of the selective inhibitors of these enzymes, phosphoramidon and captopril. Dexamethasone reduced the substance P-induced extravasation by 57% but did not affect the PAF-induced extravasation. The suppressive effect of dexamethasone on substance P-induced extravasation was completely reversed by simultaneously inhibiting NEP and ACE activities, but the inhibition of these enzymes had no effect on PAF-induced extravasation, regardless of whether the rats were pretreated with dexamethasone or not. These results suggest that NEP and ACE mediate a selective inhibitory effect of glucocorticoids on neurogenic plasma extravasation.
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PMID:Neutral endopeptidase and kininase II mediate glucocorticoid inhibition of neurogenic inflammation in the rat trachea. 171 45

We studied the effects of neutral endopeptidase (NEP) and angiotensin-converting enzyme (ACE) inhibition on the airway responses and the recovery of endogenously released substance P- and neurokinin A-like immunoreactivities (SP-LI and NKA-LI) after tracheal injection of capsaicin in isolated guinea pig lungs superfused through the trachea. Capsaicin in doses from 10(-10) to 10(-7) mol induced a dose-dependent increase in airway opening pressure and release of SP-LI and NKA-LI. Airway opening pressure changes and the recovery of SP-LI and NKA-LI were significantly greater in lungs superfused with the NEP inhibitor SCH 32615 than in control lungs. ACE inhibition with captopril did not increase the mechanical response or the recovery of SP-LI compared with lungs not receiving captopril. In lungs from guinea pigs pretreated with high doses of capsaicin 7-10 days before study, a regimen designed to deplete endogenous tachykinins, there was a significant decrease in the content and release of NKA-LI and SP-LI. There were no detectable airway effects of acute capsaicin infusion even after doses of 10(-5) mol. Because NEP is important in modulating the airway effects of endogenously released tachykinins after tracheal infusion of capsaicin, but ACE is not, it seems likely that tracheal administration of capsaicin releases tachykinins from epithelial rather than endothelial loci.
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PMID:Capsaicin-induced release of tachykinins: effects of enzyme inhibitors. 171 6

We have previously shown that neutral endopeptidase (NEP; EC 3.4.24.11) regulates neuropeptide-induced responses. Recently, Pierart et al. reported that NEP degraded purified interleukin-1 (IL-1) using thymocyte proliferation assay. Since IL-1 is an important cytokine in the immune response and inflammation, we have assessed whether NEP hydrolyzes recombinant human IL-1 beta using three assay systems (bioassay, immunoassay, and HPLC analysis). NEP on the NALM-6 cells (both intact cells and the solubilized plasma membrane fraction) efficiently hydrolyzed Met5-enkephalin and substance P. However, NEP did not significantly decrease the amount of rhIL-1 beta assessed by the growth inhibitory activity of a human melanoma, by the immunoassay, or by the direct analysis on HPLC. Therefore, we conclude that NEP does not significantly hydrolyze rhIL-1 beta. Our results suggest that, in contrast to the regulatory role of NEP in neuropeptide-induced responses, NEP is not a regulatory enzyme for IL-1-induced responses.
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PMID:Neutral endopeptidase (EC 3.4.24.11) does not hydrolyze recombinant human interleukin-1 beta. 171 45

We have compared the contractile responses of substance P (SP) and neurokinin A (NKA) to that of the non degradable muscarinic agonist, carbachol, in small and large human airways in vitro. We have also investigated the effects of the neutral endopeptidase (NEP) inhibitor, thiorphan (100 microM) on these responses. NKA contracted large and small airways to a different extent (56% vs 92% of carbachol maximal contraction, respectively). NKA was significantly less potent in large vs small bronchi (EC50 = 150 +/- 15 vs 12 +/- 5 nM respectively, p less than 0.05). SP had a lower contractile effect in large (26% carbachol maximum) and small airways (59%) with EC50 values higher than 0.5 microM. The enkephalinase inhibitor thiorphan shifted the concentration-response curve to NKA to the left in large (EC50 = 35.2 +/- 8.2 nM) and small bronchi (EC50 = 2.8 +/- 1.3 nM, p less than 0.02). This shift was associated with an increase in the maximal contraction to NKA (75% in large vs 123% in small bronchi). The amplitude of contraction to SP was also potentiated in large (45%) and in smaller bronchi (101%). In conclusion, we have demonstrated that NKA has a significantly greater constrictor effect than a cholinergic agent in more peripheral human airways in vitro. This suggests that non cholinergic constrictor pathways are more likely to be important in more peripheral airways.
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PMID:Effect of tachykinins in small human airways. 171 42

A novel ligand, [4,5-3H-Leu10]substance P ([3H]SP), with high specific activity (137 Ci/mmole) was utilized to investigate the properties of NK (neurokinin)-1 receptors on guinea pig lung membranes (GPLM) and compared them to NK-1 receptors on rat submaxillary glands (RSGM). In the presence of a neutral endopeptidase inhibitor, thiorphan (100 microM), [3H]SP bound with high specificity (greater than 95%), rapidly (k1 = 0.116 nM-1 x min-1) and in a reversible (k-1 = 0.012 min-1) manner to a single class of high-affinity (Kd = 0.16 nM) and saturable (Bmax = 256 fmol/mg protein) receptors. High specific binding with higher density (5-fold) was also detected in RSGM, albeit with a lower affinity (Kd = 1.36 nM). Guanyl-5'-yl-imidodiphosphate and guanosine-5'-O-3-thiotriphosphate inhibited binding to GPLM (and RSGM) in a concentration-related manner. In GPLM, this effect was mediated by a reduction in affinity, mainly via enhancement of ligand dissociation rates and appearance of a lower affinity state (Kd = 3.4 nM). Preincubation of GPLM with sulfhydryl modifying agents (p-chloromercuriphenyl sulfonic acid and N-ethylmaleimide) reduced receptor density and affinity in a time- and concentration-dependent manner. Competition experiments with tachykinins and analogs illustrated a rank order of potency of: SP greater than or equal to [Sar9,Met(O2)11]SP greater than SP-methyl ester greater than or equal to physalaemin greater than SP(6-11) much greater than kassinin greater than neurokinin A = eledoisin much greater than neurokinin B greater than Nle10-NKA(4-10), clearly demonstrating that these receptors are of NK-1 type. Moreover, analysis of over 30 peptide and non-peptide hormones and antagonists demonstrated exquisite selectivity (greater than 10,000-fold) towards NK-1-selective agonists (vs. other ligands. A highly significant (P less than .005) linear correlation (r = 0.924) exists between agonist affinities in GPLM and RSGM. Combined, the data suggest that [3H]SP labels a nearly homogeneous population of high-affinity, G-protein coupled NK-1 receptors on GPLM and RSGM, with very high degree of selectivity.
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PMID:Binding of the novel ligand [4,5-3H-Leu10]substance P to high-affinity NK-1 receptors on guinea pig lung membranes: modulation by GTP analogs and sulfhydryl modifying agents. 171 78

Neurogenic inflammation, due to release of neuropeptides from sensory nerves, has been demonstrated in airways of several species, particularly rodents, and may contribute to the inflammatory response in asthmatic airways. Tachykinins (substance P and neurokinin A) and calcitonin-gene-related peptide released from airway sensory nerves may cause bronchoconstriction, vasodilatation, plasma exudation and mucus secretion. Sensory nerves may become sensitised by inflammatory products and triggered by mediators such as bradykinin, resulting in exaggerated inflammation. The effects of tachykinins may be further amplified by loss of the major degrading enzyme, neutral endopeptidase, from epithelial cells. Several strategies for reducing neurogenic inflammation are possible.
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PMID:Neurogenic inflammation in airways. 171 92

The physiological effects of the tachykinin peptides substance P (SP) and neurokinin A (NKA) are limited by their microenvironmental degradation. We used the isolated tracheally superfused guinea pig lung to examine the importance of various degradative enzymes in limiting the physiological effects of exogenously administered and endogenously released tachykinins. When SP and NKA are administered via the airway epithelium, neutral endopeptidase (NEP; EC 3.4.24.11) is the major degradative enzyme as indicated by the effects of NEP inhibitors alone compared to the effects of a NEP inhibitor along with a cocktail of other peptidase inhibitors. The effects of enzyme inhibitors on physiological responses is mirrored in the amounts of peptide recovered from lung perfusates as determined using an enzyme-linked immunosorbent assay. We found similar effects when SP and NKA were released endogenously by the acute infusion of capsaicin. These data indicate that NEP is the predominant degradative enzyme modulating the effects of SP and NKA administered via the airways.
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PMID:Peptidase modulation of the pulmonary effects of tachykinins. 171 94

It was shown in two different provocation models (nasal and bronchial provocation) that substance P (SP) may play an important role in the neurogenic inflammatory response in upper and lower airway disease. (1) Pretreatment with SP augments the antigen challenge response of the nasal mucosa. (2) The baseline bronchoalveolar lavage (BAL) concentrations of SP are elevated 8-fold in allergies (pollen asthma) as compared with normals, even outside of season. (3) The SP concentration in BAL increases significantly (p less than 0.05) after bronchial allergen provocation. These findings support a previous hypothesis of an abnormally elevated activity of nonadrenergic-noncholinergic excitatory nerves and are in accordance with the results of a decreased activity of neutral endopeptidase exaggerating neurogenic inflammatory responses in the airways, including bronchomotor tone hyperresponsiveness.
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PMID:The possible role of substance P in the allergic reaction, based on two different provocation models. 171 96

We studied the effect of substance P (SP) on the electric properties of cultured canine tracheal epithelium and its possible modulation by neutral endopeptidase (NEP) by Ussing's short-circuited technique in vitro. Addition of SP (5 x 10(-6) M) to the mucosal side increased short-circuit current (SCC) from 5.1 +/- 0.9 to 10.3 +/- 2.2 microA/cm2 (mean +/- SE; p less than 0.01), which was accompanied by increases in transepithelial potential difference and conductance. The effect of the mucosal SP on SCC was dose-dependent, with the maximal increase from the baseline value being 5.8 +/- 1.0 microA/cm2 observed at 5 x 10(-5) M. The NEP inhibitor phosphoramidon (10(-5) M) did not affect these responses. On the other hand, SCC was not altered by the addition of SP to the submucosal side. However, it was increased dose-dependently in the presence of phosphoramidon (10(-5) M) but not in the presence of captopril, bestatin or leupeptin. This stimulatory effect of submucosal SP was abolished by furosemide, diphenylamine-2-carboxylate and Cl-free medium, but not by amiloride. These results suggest that SP may selectively stimulate Cl secretion across the airway epithelium and that this effect may be modulated by submucosal NEP.
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PMID:Effect of neutral endopeptidase inhibition on substance-P-induced increase in short-circuit current of canine cultured tracheal epithelium. 171 8

The release of substance P- and neurokinin A-like immunoreactivities (SP-LI and NKA-LI) after tracheal infusion of histamine, methacholine, leukotriene D4, and platelet-activating factor was measured in isolated guinea pig lungs superfused through the trachea. Infusion of each of these agonists was associated with a significant (P less than 0.05) increase in the recovery of both SP-LI and NKA-LI from lung perfusates compared with preinfusion baseline recoveries of these peptides. After infusion of bronchoactive mediators, approximately 4-15 times more NKA-LI than SP-LI was recovered from the lung superfusate. Coincident with the release of neuropeptides, mediator infusion was accompanied by an increase in airway opening pressure (Pao). Addition to the perfusate of the neutral endopeptidase inhibitor thiorphan, 1 microM increased the change in Pao induced by histamine (10(-8) mol, P less than 0.005) and methacholine (10(-8) mol, P less than 0.02) and increased the recovery of NKA-LI (P less than 0.05 for histamine and methacholine). Addition of isoproterenol to the perfusion buffer reduced, but did not abolish, either the Pao response or the increased recovery of NKA-LI (P less than 0.05) observed after histamine infusion. We conclude that bronchoactive agonists have the capacity to release both SP-LI and NKA-LI, and we speculate that NKA contributes to the bronchomotor response observed in response to histamine or methacholine.
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PMID:Release of tachykinins by histamine, methacholine, PAF, LTD4, and substance P from guinea pig lungs. 172 49


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