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)

Substance P (SP) is one of the endogenous tachykinin peptides implicated in neurogenic inflammation and may be critically involved in diseases as diverse as asthma, arthritis and inflammatory bowel disease. The current study was initiated to identify a rich source of SP receptor that would be amenable for studying the regulatory mechanism of the receptor. By using a radioligand receptor binding technique, sheep ileal smooth muscle membranes showed a much higher density of [3H]SP specific binding than other non-neural rat or sheep tissues and organs surveyed. Of the protease inhibitors tested, only phosphoramidon, a specific and potent enkephalinase inhibitor, prevented the degradation of [3H]SP and enhanced [3H]SP binding to the membrane. [3H]SP binding to the specific binding sites in the membranes was time-dependent and reached a steady state after 60 min at 22 degrees C in 25 mM Tris.NH3 (pH 7.4). Calcium and magnesium ions enhanced [3H]SP specific binding. Saturation binding studies showed that the dissociation constant (KD) and the density of maximum binding sites for [3H]SP specific binding were 0.54 nM and 83 fmol/mg of protein, respectively. The specificity of the [3H]SP labeled sites was SP greater than (4-11) SP greater than eledoisin greater than spantide greater than neurokinin-A greater than D-Pro2D-Phe7D-Trp9-SP. Neurokinin-B and senktide showed no inhibition of [3H]SP binding.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Identification and characterization of the substance P receptor in sheep intestinal smooth muscle membranes. 169 67

The effects of inhaled bradykinin (BK), substance P (SP), and neurokinin A (NKA) on pulmonary resistance and airway responsiveness to carbachol were studied in conscious allergic sheep. Inhaled BK (20 breaths, 0.1 to 5.0 mg.ml-1) caused dose-dependent increases in pulmonary resistance. Neither inhaled SP nor NKA (20 breaths, 0.1 to 1.0 mg.ml-1) produced significant bronchoconstriction in allergic sheep. However, the response to SP could be enhanced (p less than 0.05) by pretreatment with the neutral endopeptidase inhibitor, thiorphan (40 breaths, 1 mg.ml-1). Sheep that were allergic to Ascaris suum antigen were 5.9 times (p less than 0.05) more sensitive to the constrictor effects of BK than nonallergic sheep. BK-induced bronchoconstriction was blocked in a dose-dependent fashion by the BK beta 2-receptor antagonist, NPC 567 (D-arginine[hydroxyproline3,D-phenylalanine7]BK). Atropine (0.2 mg.kg-1, intravenously) and nedocromil sodium (1 mg.kg-1 in 3 ml of saline, aerosolized) significantly inhibited the BK-induced bronchoconstriction by 97% and 43%, respectively. Chlorpheniramine (2 mg.kg-1, intravenously) had no effect. NKA caused a transient increase in airway responsiveness in allergic sheep, producing a mean 1.9-fold leftward shift in dose-response curves to aerosolized carbachol (p less than 0.05). This hyperresponsiveness was not evident 24 hours after NKA challenge. Neither SP nor BK changed airway responsiveness. Thus, in allergic sheep, inhaled BK caused a more pronounced bronchoconstriction than that observed in nonallergic sheep. The bronchoconstriction was blocked by a BK-receptor antagonist and appeared to be partially mediated via cholinergic reflexes.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Airway effects of inhaled bradykinin, substance P, and neurokinin A in sheep. 170 88

To elucidate the effect of endogenous tachykinins on neuro-effector transmission of vagal nerves, we performed in vitro experiments using guinea-pig tracheal smooth muscle. The subthreshold dose (the highest dose which did not induce any smooth muscle contraction) of capsaicin (10(-8) to 10(-7) M) increased the amplitudes of contractions evoked by electrical field stimulation (EFS) significantly, but not those by acetylcholine (ACh). The inhibitor of neutral endopeptidase, phosphoramidon (10(-7) to 10(-6) M), increased the contractions evoked by EFS significantly. The inhibitor of cholinesterase, physostigmine (10(-6) to 10(-5) M), induced smooth muscle contractions, but such contractions were inhibited by atropine, suggesting the spontaneous release of ACh from the vagal nerve terminals. The subthreshold dose of substance P or capsaicin increased the contractions evoked by physostigmine. These results indicated that endogenous tachykinins increase the spontaneous ACh release as well as the ACh release in response to vagal stimulation from the nerve terminals. Furthermore, it is suggested that the excitatory effects of the tachykinins on the vagal neuro-effector transmission may be modulated by neutral endopeptidase in the guinea pig.
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PMID:Effect of endogenous tachykinins on neuro-effector transmission of vagal nerve in guinea-pig tracheal tissue. 170 39

In halothane-anesthetized and -ventilated cynomologus macaque monkeys, the effects of administering vehicle (n = 3) or the neutral endopeptidase inhibitor N-[L-(1-carboxy-2-phenyl)ethyl]-L-phenylalanyl-beta-alanine (16 mg/kg, n = 5; or 100 mg/kg, n = 3, intravenously) was examined. Cisternal CSF aliquots were examined by radioimmunoassay: 1) for Met enkephalin; 2) after trypsin and carboxypeptidase B treatment for encrypted enkephalin (X-ENK); 3) for substance P; and 4) for unmetabolized drug. Similar measures were carried out in femoral artery and femoral venous plasma, except that substance P was not assayed. In CSF, prior to drug, low, but measurable levels of enkephalin (61 pg/ml), X-ENK (285 pg/ml) and substance P (16 pg/ml) were observed. Vehicle-injected animals showed no change from baseline levels over a 4-hr sampling period in either plasma or CSF levels. In contrast, following 16 mg/kg, in CSF, there was a significant 9-fold increase in MET and 11-fold increase in X-ENK at 30 min. CSF-substance P levels rose also by a factor of 2, with the peak effect observed at 60 min. All levels displayed a significant reduction by 4 hr. There was no statistical difference between the maximum effects observed with either the 16- or 100-mg/kg dose. Plasma peptide levels of enkephalin and X-ENK were not altered by drug. CSF displayed significant drug levels by 30 min, which were between 0.1 and 1% of levels observed concurrently in plasma.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effects of [N-(L-(1-carboxy-2-phenyl)ethyl]-L-phenylalanyl-beta-alanine (SCH32615), a neutral endopeptidase (enkephalinase) inhibitor, on levels of enkephalin, encrypted enkephalins and substance P in cerebrospinal fluid and plasma of primates. 170 28

This study was designed to evaluate the mechanism of action of toluene diisocyanate (TDI) and the role of endogenous neutral endopeptidase in modulating in vitro contractile responses to TDI in guinea pigs. TDI (0.01-1 mM) produced a concentration-dependent contraction of the guinea pig main bronchi. Sensory nerve desensitization with capsaicin greatly reduced and in some cases almost abolished TDI-induced contractions. The neutral endopeptidase inhibitor phosphoramidon significantly increased the contractile response to TDI. Pretreatment with the substance P antagonist (D-Arg1,D-Pro2,D-Trp7,9,Leu11)-substance P greatly reduced TDI-induced contractions. These results suggest that TDI activates the "efferent" function of capsaicin-sensitive sensory nerves and that neutral endopeptidase may play a role in modulating the response in guinea pigs.
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PMID:Toluene diisocyanate contracts guinea pig bronchial smooth muscle by activating capsaicin-sensitive sensory nerves. 170 29

The catabolism of substance P and bradykinin, two peptides involved in inflammation, by human neutrophils was investigated. Substance P was cleaved by unstimulated neutrophils, but the rate of hydrolysis increased greatly (about 4-fold) when the cells were lysed by freezing and thawing or stimulated to release with fMet-Leu-Phe and cytochalasin B. The enzyme responsible for cleaving substance P was cathepsin G, hydrolyzing the Phe7-Phe8 bond. Neutral endopeptidase 24.11 (enkephalinase) became the main inactivating enzyme only when neutrophil cytoplasts (containing plasma membrane but no subcellular particles) or washed plasma membrane enriched high speed sediments were tested. Subcellular fractionation showed the highest substance P degrading activity to be in the granules. Purified cathepsin G readily cleaved substance P with a Km of 1.13 MK, a kcat of 6.35 sec-1 and a kcat/Km of 5639 M-1 sec-1, similar to kinetic constants previously reported for the best peptide substrates of cathepsin G. Despite the high Km, purified cathepsin G did hydrolyze SP at a much lower substrate concentration (down to 1 nM) as determined by radioimmunoassay. Bradykinin was also hydrolyzed by intact neutrophils but, in contrast, was not inactivated by cathepsin G, but by neutral endopeptidase at the Pro7-Phe8 bond. The inactivation of bradykinin by intact neutrophils was decreased by phorbol 12-myristate 13-acetate, probably due to down-regulation by endocytosis of the neutral endopeptidase on the plasma membrane. Thus, both bradykinin and substance P are inactivated by human neutrophils, although by different enzymes. In spite of the less favorable kinetics in vitro than with neutral endopeptidase, cathepsin G is the main inactivator of substance P in neutrophils. This may be due to the estimated 300 to 3600-fold higher concentration of cathepsin G in neutrophils than that of the neutral endopeptidase.
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PMID:Metabolism of substance P and bradykinin by human neutrophils. 170 55

The mechanism by which substance P induces contraction of airway smooth muscle has been the subject of numerous reports. It has been suggested that in rabbit airways the action of substance P is indirect, via the release of endogenous acetylcholine, whereas this is not so in other species. The present detailed study investigated whether substance P-induced contraction in rabbit isolated bronchus and trachea is due to the release of endogenous acetylcholine or in bronchus is due to histamine release and whether substance P is metabolized by the enzymes enkephalinase and acetylcholinesterase. Isometric contraction to cumulative addition of substance P was measured in the presence of 10(-6) and 10(-4) M atropine, 10(-6) M pyrilamine, 10(-5) M phosphoramidon, or 3 x 10(-7) M neostigmine. Neither atropine nor pyrilamine had any effect on the substance P responses. Phosphoramidon, however, produced a 12-fold shift to the left in the response curve with a decrease in the 50% effective concentration from 7.0 x 10(-8) to 6.1 x 10(-9) M (n = 4 control and 5 treated; P less than 0.05). In contrast, neostigmine at a concentration that produced a sixfold shift to the left in the acetylcholine response curve had no effect on substance P responses. We conclude that, in rabbit airways in vitro, substance P-induced contraction is not mediated by release of endogenous acetylcholine or histamine. In addition, endogenous enkephalinase but not acetylcholinesterase may be involved in the degradation of substance P. Our results show that, in contrast to previous studies in rabbits, the mechanism of action of substance P may resemble that described in humans.
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PMID:Substance P-induced contraction of rabbit airways: mechanism of action. 170 58

We examined the role of substance P (SP) and neurokinin A (NKA) in the postmortem bronchoconstriction in guinea pig lungs using isolated lungs superfused via the trachea. Airway opening pressure (Pao) during superfusion was monitored and the superfusate collected for analysis of SP- and NKA-like immunoreactivities (SP-LI and NKA-LI, respectively). Peak Pao (39.0 +/- 3.9 cmH2O) was reached 10 min after starting superfusion; Pao decreased slowly thereafter, reaching only 9.9 +/- 2.2% of the peak value 2 h after starting superfusion (P less than 0.005); 12.6 +/- 2.6 and 34.0 +/- 9.7 fmol of SP-LI and NKA-LI, respectively, were found in the fraction corresponding to 10-20 min of superfusion. Recovered immunoreactivities decreased to 5.2 +/- 0.3 and 9.3 +/- 1.8 fmol of SP-LI and NKA-LI, respectively, in the fraction corresponding to 110-120 min of superfusion (P less than 0.05). Inhibition of neutral endopeptidase with thiorphan resulted in significantly greater increases in Pao (P less than 0.005) and augmentation of the recovery of SP-LI and NKA-LI (P less than 0.05 and P less than 0.001, respectively). Capsaicin treatment of animals 7-10 days before the removal of their lungs abolished the increase in Pao during superfusion and resulted in a significant decrease in the amount of SP-LI and NKA-LI recovered. Our data confirm that tachykinin release occurs during postmortem bronchoconstriction in guinea pig lungs and, furthermore, that tachykinin degradation by NEP modulates the intensity of this response.
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PMID:Tachykinin recovery during postmortem bronchoconstriction in guinea pig lungs. 170 33

1. We have examined the effect of calcitonin gene-related peptide (CGRP) on basal mucus volume, lysozyme and albumin outputs from the ferret whole trachea in vitro, and on the outputs produced by methacholine and substance P (SP). We have also examined the effect of inhibiting neutral enkephalinase with thiorphan on the responses to CGRP. 2. CGRP (1-100 nM) produced small concentration-dependent increases in basal mucus volume, lysozyme and albumin outputs. These effect of CGRP were enhanced by thiorphan. The increases in basal outputs with CGRP and the potentiation by thiorphan were considerably less than previously observed with SP and neurokinin A (NKA). CGRP had no significant effect on potential difference (PD) across the trachea. 3. CGRP produced a concentration-dependent inhibition of methacholine- and SP-induced lysozyme output but a concentration-dependent increase in methacholine- and SP-induced albumin output. The effects of CGRP on methacholine-induced lysozyme and albumin outputs were enhanced by thiorphan. CGRP weakly inhibited methacholine-induced mucus volume output and weakly enhanced SP-induced mucus volume output. 4. Thus, CGRP weakly stimulates basal serous cell secretion and epithelial albumin transport, but does not alter epithelial integrity. CGRP inhibits the serous cell secretion due to methacholine or SP, but potentiates the epithelial albumin transport produced by these agents. The interaction between CGRP and other sensory neuropeptides or muscarinic agonists on airway submucosal glands and epithelium may be important in the normal airway and in inflammatory airway diseases where release of sensory neuropeptides is enhanced.
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PMID:The effects of calcitonin gene-related peptide on submucosal gland secretion and epithelial albumin transport in the ferret trachea in vitro. 171 May 27

To determine the roles of endogenously released tachykinins (substance P, neurokinins A and B) in human bronchial tissues, and to determine the roles of enkephalinase (neutral endopeptidase, E.C. 3.4.24.11) in regulating the effects of the tachykinins, we studied the effects of substance P and capsaicin, which releases tachykinins, on human bronchial smooth muscle contraction in the presence or absence of enkephalinase inhibitor phosphoramidon in vitro. Substance P alone caused human bronchial smooth muscle contraction at 10(-6) M or more. Phosphoramidon (10(-7) to 10(-5) M) potentiated the substance P-induced contraction in a dose-dependent fashion, and phosphoramidon shifted the dose-response curve to lower concentrations. Capsaicin (10(-5) or 10(-4) M) alone caused bronchial smooth muscle contraction in four tissues from nine patients. After the contraction by capsaicin reached a plateau, phosphoramidon (10(-5) M) increased and prolonged the contraction significantly. Furthermore, pretreatment of bronchial tissues with phosphoramidon (10(-5) M) potentiated capsaicin-induced contraction in all tissues from five patients. Phosphoramidon (10(-5) M) shifted the dose-response curve to capsaicin to lower concentrations more than 1 log unit. Captopril did not alter the contractile response to substance P, suggesting that angiotensin-converting enzyme does not regulate the contractile response to substance P in human bronchial smooth muscle in vitro. These results suggest that enkephalinase regulates the contractile effects of exogenous substance P and endogenous substances, probably tachykinins, released by capsaicin in the human bronchus.
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PMID:Enkephalinase inhibitor potentiates substance P- and capsaicin-induced bronchial smooth muscle contractions in humans. 171 Aug 81


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