Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.24.11 (CD10)
 9,792 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The tachykinins substance P (SP) and neurokinin A (NKA) have been shown to induce airway smooth muscle contraction in mature animals, and the enzyme neutral endopeptidase (NEP) modulates this effect. We evaluated maturation of SP- and NKA-induced tracheal smooth muscle contraction and modulation of their effects by NEP in anesthetized, paralyzed, and artificially ventilated piglets less than 4 days, 2-3 wk, and 10 wk of age. Tracheal smooth muscle tension was measured in vivo from an open tracheal segment by use of a force transducer. Intravenous SP caused a dose-dependent increase in tracheal tension in all three age groups; however, the response in less than 4-day-old piglets was significantly weaker than in 2- to 3- and 10-wk-old piglets. NKA caused a dose-dependent increase in tracheal tension only in 2- to 3- and 10-wk-old piglets. The response of tracheal tension to NKA was weaker than the response to SP in all age groups. Atropine (2 mg/kg) significantly diminished the responses of tracheal tension to SP and NKA, indicating a cholinergic contribution to these responses at all ages. Intravenous thiorphan, a known NEP inhibitor, potentiated the effects of SP only in 2- to 3- and 10-wk-old piglets and did not affect the response of tracheal tension to NKA at any age. Biochemical analyses demonstrated a significant increase in tracheal NEP activity in comparably aged piglets over the first 10 wk of life.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Tracheal smooth muscle responses to substance P and neurokinin A in the piglet. 137 11

The effect of ozone (3 ppm, 15-120 min) on bronchial reactivity in the guinea-pig was studied. Ozone induced marked (6-250-fold) bronchial hyperreactivity (BHR) to a range of inhaled, but not intravenous bronchoconstrictors. The degree of BHR was related to the duration of prior ozone exposure. The glutathione redox status was shifted to a more oxidized state in lung after 120 min ozone treatment, although no changes were found in the energy status of lung tissue, as judged by the concentrations of adenosine phosphates. Ascorbic acid pretreatment prevented BHR induced by 30 min ozone exposure. Neutral endopeptidase inhibitors elicited BHR to both substance P and histamine, but did not further enhance bronchoconstriction to substance P after ozone exposure for 120 min. Neither mepyramine, fentanyl, indomethacin nor a 5-lipoxygenase inhibitor (BW B70C), given prior to ozone exposure prevented the induction of BHR to histamine. Atropine or bilateral vagotomy reduced BHR after a 120-min, but not 30-min exposure to ozone. We conclude that in the guinea-pig, ozone induces non-specific, route-dependent BHR by oxidative injury, reducing airway NEP activity and enhancing the cholinergic and peptidergic component to bronchoconstriction. Neither cyclooxygenase nor 5-lipoxygenase products appear to play a role in ozone-induced BHR in this animal model.
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PMID:Mechanisms contributing to ozone-induced bronchial hyperreactivity in guinea-pigs. 137 22

The purpose of the study was to determine the extent that peptidergic afferent and efferent pathways contribute to vagally induced vasodilation in the trachea of the dog. The change in vascular resistance of the tracheal branch of the cranial thyroid artery and the trachealis responses were determined in 28 anesthetized, paralyzed, and mechanically ventilated dogs. After propranolol (2 mg/kg) and phentolamine (1.5 mg/kg), stimulation of the superior laryngeal nerves (NS; 15 Hz, 7 V, 2 ms, 30 s) caused a decrease in vascular resistance of 11.7 +/- 0.8% and a tracheal contraction of 5.2 +/- 4.7 cmH2O. Atropine (1.5 mg/kg) reduced the fall in vascular resistance to 4.7 +/- 0.8% (P less than 0.01), whereas tracheal contraction was abolished. Thiorphan (1.5 mg), a neutral endopeptidase inhibitor, augmented the decrease in vascular resistance (8.8 +/- 0.6%; P less than 0.01) to NS. After hexamethonium (0.5 mg/kg), NS still caused a small decrease in TVR (2.9 +/- 0.9%; P less than 0.05), which was abolished by capsaicin. In atropinized dogs, capsaicin reduced the fall in vascular resistance after NS; the residual vasodilation was virtually abolished by hexamethonium. Acetylcholine (10(-3) mg/kg) decreased vascular resistance (15.7 +/- 3.0%), and the effect was abolished by atropine. We conclude that there is noncholinergic nonadrenergic vagally induced tracheal vasodilation that is peptidergic. The peptidergic vasodilation appears to be mediated by both afferent and efferent pathways.
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PMID:A peptidergic component to vagally induced tracheal vasodilation in the dog. 140 22

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

Sodium metabisulfite (MBS), a commonly used preservative, induces bronchoconstriction in asthmatics, probably through the release of sulfur dioxide (SO2). The mechanisms involved in MBS- and SO2-induced bronchoconstriction are not yet certain. We aerosolized MBS or acid control solution (pH, 2.7) to anesthetized, tracheostomized guinea pigs pretreated intravenously with propranolol (1 mg/kg). MBS was given at increasing doubling concentrations (0.01, 0.02, 0.04, and 0.08 M) every 5 min. Steep concentration-response curves were observed, and most animals responded at 0.02 or 0.04 M. Tachyphylaxis was seen at high concentrations and during a subsequent MBS challenge 15 min later. For pharmacologic studies, we stopped the challenge when lung resistance (RL) had increased by at least 350%; a second challenge was found to be reproducible. MBS response was measured as the concentration needed to increase RL by 350% (PC350). Atropine (1 mg/kg given intravenously) did not affect PC350 or the peak RL response. Inhibition of neutral endopeptidase by inhaled phosphoramidon (7.5 nmol) administered before the repeated challenge did not alter PC350 value to MBS or peak RL responses (phosphoramidon, 201 +/- 49% of first peak; vehicle, 164 +/- 35%). In addition, the increase in RL was not prolonged in the phosphoramidon-treated group. Animals treated subcutaneously with capsaicin (50 mg/kg) 1 wk before the experiment, so as to deplete neuropeptides from airway sensory nerves, had PC350 values similar to those of the control animals. Our data demonstrate that inhaled MBS causes bronchoconstriction in guinea pigs by mechanisms that are due neither to a cholinergic reflex nor to the release of tachykinins from airway sensory nerves.
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PMID:Bronchoconstriction induced by inhaled sodium metabisulfite in the guinea pig. Effect of capsaicin pretreatment and of neutral endopeptidase inhibition. 225 57

To determine the role of endogenous enkephalinase (EC 3.4.24.11) in regulating peptide-induced contraction of airway smooth muscle, we studied the effect of the enkephalinase inhibitor, leucine-thiorphan (Leu-thiorphan), on responses of isolated ferret tracheal smooth muscle segments to substance P (SP) and to electrical field stimulation (EFS). Leu-thiorphan shifted the dose-response curve to SP to lower concentrations. Atropine or the SP antagonist [D-Pro2,D-Trp7,9]SP significantly inhibited SP-induced contractions in the presence of Leu-thiorphan. Leu-thiorphan increased the contractile responses to EFS dose dependently, an effect that was significantly inhibited by the SP antagonist [D-Pro2,D-Trp7,9]SP. SP, in a concentration that did not cause contraction, increased the contractile responses to EFS. This effect was augmented by Leu-thiorphan dose dependently and was not inhibited by hexamethonium or by phentolamine but was inhibited by atropine. Because contractile responses to acetylcholine were not significantly affected by SP or by Leu-thiorphan, the potentiating effects of SP were probably on presynaptic-postganglionic cholinergic neurotransmission. Captopril, bestatin, or leupeptin did not augment contractions, suggesting that enkephalinase was responsible for the effects. These results suggest that endogenous tachykinins modulate smooth muscle contraction and endogenous enkephalinase modulates contractions produced by endogenous or exogenous tachykinins and tachykinin-induced facilitation of cholinergic neurotransmission.
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PMID:Enkephalinase inhibitor potentiates substance P- and electrically induced contraction in ferret trachea. 244 55

1. Cholecystokinin-octapeptide (CCK-OP, 10(-10)-3 x 10(-6) M) produced a concentration-dependent contractile response in guinea-pig trachea which was enhanced by both the mechanical removal of the epithelium and by indomethacin (10(-5) M), with an EC50 of 6.18 +/- 0.10 x 10(-8) M. 2. Sub-threshold concentrations of CCK-OP, which did not alter the resting tone of the smooth muscle, did not alter responses produced to electrical field stimulation (EFS) or to vagal nerve stimulation in an intact tracheal tube preparation. Atropine (2 x 10(-6) M) did not alter the concentration-response curve to CCK-OP, indicating that CCK-OP contraction is not mediated by cholinergic mechanisms. 3. The inhibition of neutral endopeptidase (endopeptidase-24.11) by phosphoramidon (10(-5) M) gave a leftward shift in the CCK-OP concentration-response curve in tissues with intact epithelium obtained from normal animals, but had no effect in tissues denuded of epithelium or in tissues obtained from animals which had been actively sensitized and challenged with ovalbumin (OA). 4. CCK-OP-induced contractile responses were antagonized by the CCK-receptor antagonists dibutyryl cyclic guanosine monophosphate (pA2 = 4.3) and L-364,718 (pA2 = 9.6). 5. CCK-OP induced bronchoconstriction in large, but not small, human airways and was antagonized by the CCK-receptor antagonist L-364,718. CCK-OP had no effect on cholinergic neural responses elicited by EFS in human airways.
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PMID:Cholecystokinin-octapeptide constricts guinea-pig and human airways. 275 37

Neurokinin A (NKA), substance P (SP), and neurokinin B (NKB) enhanced the contractile force of uterine preparations from estrogen-treated rats. Neurokinin A was more and NKB less potent than SP. The actions of SP were enhanced by phosphoramidon (1 microM) but were unaffected by captopril (10 microM) or bestatin (10 microM). The actions of the peptides were enhanced in the combined presence of phosphoramidon, captopril, and bestatin; the potency order remained NKA > SP > NKB. Atropine inhibited responses to NKB but not to NKA, and slightly reduced those to SP. Specific binding of [125I]-iodohistidyl-neurokinin A (INKA) to uterine membranes was displaced by the tachykinins with a potency order of NKA > SP > NKB. These findings indicate that in the rat uterus 1) tachykinins act at an NK-2 receptor, and that another tachykinin receptor on cholinergic nerves may also be present; and 2) endopeptidase-24.11 participates in the inactivation of the tachykinins.
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PMID:Mammalian tachykinins stimulate rat uterus by activating NK-2 receptors. 768 98

In 21 anesthetized dogs, we placed a flow probe around the right bronchial artery and examined changes in bronchial blood flow and bronchial vascular conductance when pulmonary C-fibers were stimulated by right atrial injection of capsaicin. When vagus nerves were intact, capsaicin evoked a pulmonary depressor chemoreflex and increased bronchial blood flow by 125% and bronchial vascular conductance by 175%; flow in an adjacent intercostal artery did not increase. Injection of color-coded microspheres revealed that blood flow to mucosa of lower trachea and to a peripheral bronchus doubled, whereas flow to posterior tracheal wall increased little. Cooling (to -1 degree C) or cutting cervical vagi (in 17 dogs) abolished the pulmonary chemoreflex and abolished all bronchial vascular effects in nine dogs but 33% of the vasodilation persisted in eight. In five of six dogs, this persisting vasodilation was potentiated by phosphoramidon (a neutral endopeptidase inhibitor that retards breakdown of neuropeptides released by C-fibers). Atropine reduced the capsaicin-induced bronchial vasodilation by approximately 30%. We conclude that the bronchial vasodilation was largely due to a centrally mediated vagal reflex and that a neuropeptide-dependent axon-reflex component was also present in about one-half the dogs.
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PMID:Capsaicin-induced bronchial vasodilation in dogs: central and peripheral neural mechanisms. 844 1

1. In dogs anaesthetized with pentobarbitone, electrical stimulation of the parasympathetic nerve fibres to the nasal mucosa evoked frequency dependent increases in both nasal arterial blood flow and nasal secretion. Blood flow was measured using a transonic flow probe placed around the artery. 2. Sympathetic nerve stimulation for 3 min at 10 Hz evoked significant and prolonged (> 30 min) attenuation of the vasodilator and secretory responses to subsequent parasympathetic stimulation. 3. Intravenous and intranasal administration of the neuropeptide Y (NPY) analogue N-acetyl [Leu28,Leu31] NPY 24-36, a selective NPY Y2 receptor agonist (20 nmol kg-1), significantly attenuated both vasodilator and secretory effects of subsequent parasympathetic nerve stimulation. When given intravenously, the inhibitory effect of this Y2 receptor agonist on vascular and secretory effects of parasympathetic nerve stimulation was rapid in onset (5 min) and lasted for more than 60 min. The modulatory effect of the Y2 receptor agonist was also seen with intranasal administration, but was slower in onset (15 min), and lasted less than 45 min. The effects of the intranasal pretreatment with the Y2 receptor agonist were significantly prolonged in the presence of the endopeptidase inhibitor phosphoramidon (10 nM). 4. Atropine pretreatment did not significantly reduce the change in vascular conductance evoked by parasympathetic nerve stimulation. Subsequent pretreatment with the NPY Y2 receptor agonist N-acetyl [Leu28,Leu31] NPY 24-36 reduced the stimulation induced increase in conductance by 30%. Nasal secretion was reduced by 70% following pretreatment with atropine and a further 30% by pretreatment with the NPY Y2 receptor agonist. Dose dependent vasodilator and secretory effects of local intra-arterial infusion of acetylcholine and vasoactive intestinal peptide were not modified by the NPY Y2 agonist. 5. Total protein and albumin concentration were measured in nasal lavage fluid collected after nerve stimulation. Atropine pretreatment increased the percentage of the total protein that was albumin in nasal lavage fluid. Neither sympathetic nerve stimulation nor Y2 receptor agonist pretreatment further modified the albumin exudation (a marker of vascular permeability) in nasal fluid lavage collected after parasympathetic nerve stimulation. 6. We propose that sympathetic nerve stimulation releases NPY, which acts on Y2 receptors, probably located on parasympathetic nerve endings, to attenuate both vasodilatation and nasal secretion evoked by subsequent parasympathetic nerve stimulation. This effect is also observed after pretreatment with the Y2-selective NPY analogue N-acetyl [Leu28,Leu31] NPY 24-36.
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PMID:Sympathetic and parasympathetic interaction in vascular and secretory control of the nasal mucosa in anaesthetized dogs. 945 55


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