Effect of SR-140333,a neurokinin-1 receptor antagonist,on airway reactivity to methacholine in sedated rats

目的：探讨神经激肽对乙酰甲胆碱（ＭＣ）气道反应性的作用．方法：观察非肽类ＮＫ１受体拮抗剂ＳＲ１４０３３３对镇静大鼠的ＭＣ气道反应性和离体气管条的收缩反应．结果：ＳＲ１４０３３３抑制ＭＣ气雾（１０－１０００μｍｏｌ／ｍ３）引起的呼吸频率增快，抑制ＭＣ气雾（１ｍｍｏｌ／ｍ３）反应的ＩＤ５０为４９（１４－１７２μｇ·ｋｇ－１）；ＳＲ１４０３３３１μｍｏｌ·Ｌ－１对乙酰甲胆碱引起的气管平滑肌收缩无抑制作用．阿托品可阻断ＭＣ的在体和离体反应．结论：内源性速激肽参与在体ＭＣ气道反应，至少部分由ＮＫ１受体介导．     

速激肽NK-1受体拮抗剂SR-140333对抗原引起致敏大鼠气道高反应性的影响

为观察速激肽ＮＫ１受体拮抗剂ＳＲ１４０３３３对抗原攻击引起的致敏大鼠气道高反应性的影响，测定了致敏大鼠在抗原攻击前后的基础呼吸频率，对ＭＣｈ的反应性及支气管肺泡灌洗液中的白细胞数量。实验结果显示，致敏大鼠吸入ＯＡ后６ｈ基础呼吸频率增加，并显著增加乙酰甲胆碱（ＭＣｈ）的反应性、ＭＣｈ的－ｌｏｇＰＣ３０值和支气管肺泡灌洗液中的白细胞数量。ｉｐ速激肽ＮＫ１受体拮抗剂ＳＲ１４０３３３（０１ｍｇ·ｋｇ－１）或地塞米松（０５ｍｇ·ｋｇ－１），可明显抑制上述反应，小剂量ＳＲ１４０３３３（００１ｍｇ·ｋｇ－１）仅有部分抑制作用。结果提示抗原攻击可引起致敏大鼠气道高反应性和气道炎症，速激肽ＮＫ１受体拮抗剂可抑制这些反应     

硝普钠与异丙肾上腺素松弛犬气管平滑肌的协同作用

目的：研究硝普钠（ＳＮＰ）与异丙肾上腺素（ＩＳＯ）对犬气管平滑肌松弛作用是否存在协同关系，并分析协同的机制。方法：采用放射免疫分析法测定犬气管平滑肌环核苷酸量，并用磷酸二酯酶（ＰＤＥ）同工酶抑制剂为工具分析ＳＮＰ与ＩＳＯ相互作用的机制。结果：ＳＮＰ（１～１００μｍｏｌ·Ｌ－１）增强ＩＳＯ（３０μｍｏｌ·Ｌ－１）对３μｍｏｌ·Ｌ－１乙酰甲胆碱预收缩的犬气管平滑肌的松弛作用。ＳＮＰ（１００μｍｏｌ·Ｌ－１）与ＩＳＯ（３０μｍｏｌ·Ｌ－１）对犬气管平滑肌松弛的协同作用伴有气管平滑肌中ｃＡＭＰ积聚比ＳＮＰ与ＩＳＯ单独时分别增加１．２倍与０．４倍。ＰＤＥⅤ抑制剂扎普司特（３μｍｏｌ·Ｌ－１）使ＳＮＰ的气管平滑肌ｃＧＭＰ积聚由２．４倍增加到４．６倍，可进一步增加气管松弛作用１．２倍。合并ＰＤＥⅢ抑制剂氰胍哒嗪（３０μｍｏｌ·Ｌ－１）和ＰＤＥⅣ抑制剂咯利普兰（３０μｍｏｌ·Ｌ－１）或合并ＳＮＰ（１００μｍｏｌ·Ｌ－１）和咯利普兰（３０μｍｏｌ·Ｌ－１）均能进一步增强ＩＳＯ的气管ｃＡＭＰ积聚与松弛作用。结论：ＳＮＰ是通过气管平滑肌ｃＧＭＰ含量增加而抑制ＰＤＥⅢ，导致ＳＮＰ与ＩＳＯ对气管松弛的协同作用。     

已酮可可碱与蛋白激酶C抑制剂对佛波醇酯诱导脑微血管内皮细胞？…

目的：研究佛波醇酯（ＰＭＡ）地大鼠脑微血管内皮细胞（ＲＢＭＥＣ）表达细胞间粘附分子－１（ＩＣＡＭ－１）及ＰＫＣ抑制剂Ｈ７与已酮可可碱（ＰＴＸ）的抑制作用。方法：采用ＥＬＩＳＡ方法测定培养ＲＢＭＥＣ表达ＩＣＡＭ－１。结果：ＰＭＡ在１０－１００．Ｌ＾－１范围内剂量依赖性地诱导ＲＢＭＥＣ表达ＩＣＡＭ－１;在４－１６ｈ范围内时间依赖性诱导ＲＢＭＥＣ表达ＩＣＡＭ－１。Ｈ７和ＰＴＸ分别在５－５０μｍｏｌ．Ｌ＾     

糖尿病患者RBC—S与MAU关系的研究

观察了１１０例糖尿病人及３０例正常人的红细胞山梨醇（ＲＢＣ－Ｓ）与水微量白蛋白（ＭＡＵ）之间的关系。结果显示：（１）正常人ＲＢＣ－ＳＯ０－１μｍｏｌ／Ｌ,２４小时尿微量白蛋白（ＭＡＵ）小于２６ｍｇ（２）３组糖尿病病人ＲＢＣ－Ｓ均〉２．２５μｍｏｌ／Ｌ,且与ＭＡＵ呈正相关。（３）使用小剂量开搏通治疗后,随着ＭＡＵ的降低,ＲＢＣ－Ｓ也下降。以上结果表明,ＲＢＣ－Ｓ的变化可以作为预报早期糖尿病肾病和判断     

蝙蝠葛苏林碱对心肌细胞浆Ca^2＋活度的影响

目的：探讨蝙蝠葛苏林碱（ＤＳ）对迟后的除极的作用，方法：采用Ｃａ＾２＋敏感性电极技术，结果：毒毛旋花甙Ｇ（Ｓｔｒ，３μｍｏｌ．Ｌ＾－１）使豚鼠心肌乳头肌细胞浆Ｃａ＾２＋活度（ａｃａ）增加０．１９±０．１１μｍｏｌ．Ｌ＾－１，在出现迟后除极和触发活动（ＴＡ）时又分别增加１．４８±０．５５和４．９６±１．８１μｍｏｌ．Ｌ＾－１，标本经ＤＳ作用后，Ｓｔｒ地引起αｃａ增高和ＴＡ，ＤＳ抑制无Ｃａ＾２＋和咖啡     

美西律对海马脑片突触功能缺氧损伤的保护作用

记录大鼠海马脑片ＣＡ１区锥体细胞的群锋电位（ＰＳ）和突触前排放（ＰＶ），缺氧３ｍｉｎ时对照组ＰＳ幅度下降至０．４±０．４ｍＶ，而提前１ｈ灌流美西律（Ｍｅｘ）１０或１００μｍｏｌ·Ｌ＾－１组ＰＳ仅下降至１．２±１．２或１．５±０．４ｍＶ。复氧３０ｍｉｎ后对照组ＰＳ恢复率为１１％，Ｍｅｘ１０或１００μｍｏｌ·Ｌ＾－１组分别为４８％和６５％。可见Ｍｅｘ减慢缺氧时ＰＳ下降过程，加速度复氧时ＰＳ恢复过程，…     

4,5—二氢—6—[（苯乙酰基—哌嗪基）苯基]—5—甲基—3（2H）—哒…

４，５－二氢－６－［（苯乙酰基－哌嗪基）苯基］－５－甲基－３（２Ｈ）－达嗪酮（ＳＭⅡ４）０．１－２．５μｍｏｌ．Ｌ＾－＾１能使血小板激活因子（ＰＡＦ）及血栓素Ａ２类似物Ｕ４６６１９诱导的兔血小板聚集剂量一效应曲线左移且最大反应降低。其ｐＤ２分别为６．０±ｓ０．４及６．１±ｓ０．３．ＳＭⅡ４还能抑制ＡＤＰ，花生四烯酸（ＡＡ）及Ｕ４６６１９诱导的人血小板聚集，其ＩＣ５０分别是１．２，１．３及１．６．．     

M受体机制在粉防已碱保护心脏缺血再灌注损伤作用中的影响

目的 探讨Ｍ受体对粉防已碱抗心脏因再灌注损伤作用的影响。方法 以离体豚鼠工作心脏缺血再灌注为心肌损伤模型。观察乙酰甲胆碱（Ｍｃｈ,０．１μｍｏｌ．Ｌ＾－１）,粉防已碱（Ｔｃｈｍ,０．３μｍｏｌ．Ｌ＾－１）的心肌保护作用。结果 对照组在缺血复灌后２０ｍｉｎ,主动脉压（ＡＰ）、左室收缩压（ＬＶＳＰ）、左室压力上升最大速率（＋ｄｐ／ｄｔｍａｘ）,在 压力下降最大速率（－ｄｐ＝／ｄｔｍａｘ）仅分别恢复至缺     

高效液相色谱法测定雷登泰口服液中创木酚甘油醚,盐酸伪麻黄？…

采用高效液相色谱外标法测定雷登泰口服液中愈创木酚甘油醚，盐酸伪麻黄碱，氢溴酸右美沙芬的含量。色谱柱为ＳｐｈｅｒｉｓｏｒｂＣ８ ５μｍ４．６ｍｍ２５０ｍｍ，流动相为０．００２５ｍｏｌ．Ｌ＾－１己烷磺酸甲醇溶液－水（含２％三乙胺）－３ｍｏｌ．Ｌ＾－１磷酸（１．４：１．０：０．０６３），紫外检测器，检测波长２５７ｎｍ。结果愈创木酚甘油醚进样量在２．０－１０．０μｇ，盐酸为伪麻黄碱在０．３－１．５μｇ，氢     

速激肽NK-1受体拮抗剂SR-140333对抗原引起致敏大鼠气道高反应性的影响

为观察速激肽NK-1受体拮抗剂SR-140333对抗原攻击引起的致敏大鼠气道高反应性的影响,测定了致敏大鼠在抗原攻击前后的基础呼吸频率,对MCh的反应性及支气管-肺泡灌洗液中的白细胞数量。实验结果显示,致敏大鼠吸入OA后6h基础呼吸频率增加,并显著增加乙酰甲胆碱(MCh)的反应性、MCh的-logPC₃₀值和支气管-肺泡灌洗液中的白细胞数量。ip速激肽NK-1受体拮抗剂SR-140333(0.1mg·kg^-1)或地塞米松(0.5mg·kg^-1),可明显抑制上述反应,小剂量SR-140333(0.01mg·kg^-1)仅有部分抑制作用。结果提示抗原攻击可引起致敏大鼠气道高反应性和气道炎症,速激肽NK-1受体拮抗剂可抑制这些反应。     

Evidence for the participation of glutamate in reflexes involving afferent, substance P-containing nerve fibres in the rat.

1. Responses mediated, either peripherally or centrally, by substance P-containing primary afferent C-fibres were investigated in the rat following impairment of axonal transport by colchicine (120 micrograms kg-1, i.p., daily for 3 days), and after treatment with the tachykinin antagonist SR-140333 (10-100 micrograms kg-1, i.v.) or the N-methyl-D-aspartate (NMDA) antagonist MK-801 (100 micrograms kg-1). 2. Peripheral effects mediated by afferent C-fibres were measured by plasma protein extravasation (Evans blue method), following antidromic stimulation of the sciatic nerve, topical application of mustard oil and, as control, i.v. injection of substance P. SR-140333 (100 micrograms kg-1) reduced the effects by 86%, 75% and 74%, respectively. Colchicine reduced the effects of the first two stimuli by 31% and 33% and, as expected not the effect of substance P. The increase of paw skin temperature following capsaicin i.v. was inhibited by SR-140333, but not by colchicine. MK-801 had no effect on the plasma protein extravasation following antidromic sciatic nerve stimulation or on the rise of paw skin temperature induced by capsaicin i.v., thus excluding an effect of MK-801 on peripheral terminals of afferent neurones. 3. Depressor reflexes, which are known to be mediated by capsaicin-sensitive afferent neuones, such as those elicited (A) by a stimulating dose of 30 ng capsaicin i.a., (B) by distension of the ascending colon or (C) by afferent sciatic nerve stimulation were studied. Colchicine significantly reduced depressor reflexes A and B, but had no effect on reflex C. None of the reflexes was affected by SR-140333. MK-801 significantly inhibited all three reflexes. 4. Capsaicin, injected either i.v. (200 micrograms kg-1) or into the nucleus caudatus/putamen (i.c., 30 micrograms), induced an increase in paw skin temperature and a decrease in colon temperature. The rise in fore paw skin temperature (delta t = 2.3 +/- 0.4 degrees C) evoked by capsaicin i.v. was almost completely blocked by SR-140333 (100 micrograms kg-1, i.v.), but no inhibition was observed with MK-801, indicating that capsaicin had brought about a release of substance P from peripheral nerve terminals. Colchicine did not influence heat dissipation induced by i.v. capsaicin. 5. When capsaicin was injected i.c., the rise in paw skin temperature in colchicine- and SR-140333-pretreated groups did not differ from that of the control group. MK-801 totally prevented the heat loss reaction to i.c. capsaicin administration. Colchicine did not change the effects of i.v. or i.c. injected capsaicin: this excludes the involvement of a mechanism dependent on axonal transport of neurotransmitters. 6. The reduction of axonal transport by colchicine reduced plasma extravasation induced by mustard oil and antidromic sciatic nerve stimulation (peripheral functions) and depressor reflexes evoked by i.a. capsaicin and colon distension (central functions). It can be argued that afferent stimulation of the sciatic nerve includes the stimulation of A-fibres, which might be less sensitive to colchicine. SR-140333 was effective only on peripherally mediated responses. 7. The recent evidence for the concomitant release of glutamate and substance P from central terminals of afferent C-fibres, known to mediate reflexes abolished after capsaicin treatment allows the following conclusions: (a) the inhibition by MK-801 indicates an essential role for glutamate in the central transmission of these reflexes; (b) tachykinin antagonists such as SR-140333 do not affect these responses when administered systemically. Centrally released substance P could be involved in functions of the CNS other than those investigated here unless the access of neurokinin antagonists to their receptors in the CNS is insufficient.     

速激肽受体拮抗剂抗豚鼠过敏性哮喘的作用

实验目的是研究速激肽与哮喘的关系,评价速激肽受体拮抗剂对哮喘的治疗作用。结果表明,ip速激肽NK-1受体拮抗剂CP-96345,NK- 2受体拮抗剂SR-48968或两药合用,均可有效减少清醒致敏豚鼠吸入抗原引起的喘息反应,降低过敏性休克死亡率。SR-48968减轻麻醉豚鼠抗原引起的气道收缩,并浓度依赖性降低抗原引起的气管和支气管平滑肌收缩幅度。CP-96345可抑制抗原诱导的支气管和肺叶伊文思蓝渗出,仅对支气管平滑肌收缩有部分抑制作用。结果提示,速激肽参与哮喘发病,速激肽受体拮抗剂可抑制抗原诱导的气道平滑肌收缩(NK-2受体)和微血管渗漏(NK-1受体)而减轻哮喘反应。     

Mechanisms of the cutaneous vasodilator response to local external pressure application in rats: involvement of CGRP, neurokinins, prostaglandins and NO

1. Local pressure-induced vasodilation (PIV) is a neural vasodilator response to non-nociceptive externally applied pressure in the skin, previously described in humans. We first determined whether PIV exists in rats and depends on capsaicin-sensitive fibres as it does in humans. We then examined the mediators involved in the efferent pathway of PIV. 2. Cutaneous blood flow was measured by laser Doppler flowmetry during 11.1 Pa s(-1) increases in local applied pressure in anaesthetized rats. The involvement of capsaicin-sensitive fibres in PIV was tested in rats treated neonatally with capsaicin. To antagonize CGRP, neurokinin-1, -2, or -3 receptors, different groups of rats were treated with CGRP(8 - 37), SR140333, SR48968 or SR142801, respectively. Prostaglandins involvement was tested with indomethacin treatment. To inhibit nitric oxide synthase (NOS) activity or specific neuronal NOS, rats were treated with N(G)-nitro-L-arginine or 7-nitroindazole, respectively. 3. PIV was found in rats, as in humans. PIV was abolished by neonatal treatment with capsaicin and by administration of CGRP(8 - 37) but remained unchanged with SR140333, SR48968 and SR142801 treatments. Prostaglandin inhibition resulted in a significant decrease in PIV. Inhibition of NOS abolished PIV, whereas inhibition of neuronal NOS caused a diminution of PIV. 4. These data suggest that PIV depends on capsaicin-sensitive fibres in rats, as in humans. It appears that CGRP plays a major role in the PIV, whereas neurokinins have no role. Furthermore, PIV involves a contribution from prostaglandins and depends on endothelial NO, whereas neuronal NO has a smaller role.     

In vitro and in vivo biological activities of SR140333, a novel potent non-peptide tachykinin NK1 receptor antagonist

(S)1- {;2-[3-(3,4-dichlorophenyl)-1-(3-isopropoxyphenylacetyl)piperidin-3-yl]ethyl };-4-phenyl-1-azoniabicyclo[2.2.2]octane chloride (SR140333) is a new non-peptide antagonist of tachykinin NK₁ receptors. SR140333 potently, selectively and competitively inhibited substance P binding to NK₁ receptors from various animal species, including humans. In vitro, it was a potent antagonist in functional assays for NK₁ receptors such as [Sar⁹,Met(O₂)¹¹]substance P-induced endothelium-dependent relaxation of rabbit pulmonary artery and contraction of guinea-pig ileum. Up to 1 μM, it had no effect in bioassays for NK₂ ([βAla⁸]neurokinin A-induced contraction of endothelium-deprived rabbit pulmonary artery) and NK₃ ([MePhe⁷]neurokinin B-induced contraction of rat portal vein) receptors. The antagonism exerted by SR140333 toward NK₁ receptors was apparently non-competitive, with pD'₂ values (antagonism potency evaluated by the negative logarithm of the molar concentration of antagonist that produces a 50% reduction of the maximal response to the agonist) between 9.65 and 10.16 in the different assays. SR140333 also blocked in vitro [Sar⁹,Met(O₂)¹¹]substance P-induced release of acetylcholine from rat striatum. In vivo, SR140333 exerted highly potent antagonism toward [Sar⁹,Met(O₂¹¹]substance P-induced hypotension in dogs (ED₅₀ = 3 μg/kg i.v., bronchoconstriction in guinea-pig (ED₅₀ = 42 μg/kg i.v.) and plasma extravasation in rats (ED₅₀ = 7 μg/kg i.v.). Finally, it also blocked the activation of rat thalamic neurons after nociceptive stimulation (ED = 0.2 μg/kg i.v.).     

The antimigraine drug, sumatriptan (GR43175), selectively blocks neurogenic plasma extravasation from blood vessels in dura mater.

1. We describe the actions of GR43175, a 5-hydroxytryptamine1 (5-HT1)-like receptor agonist, on neurogenically-mediated plasma protein extravasation within an important pain-sensitive intracranial tissue, the dura mater. 2. GR43175 markedly attenuated extravasation of 125I-albumin from blood vessels within ipsilateral dura mater when administered to rats (100 micrograms kg-1) fifteen minutes before unilateral electrical trigeminal stimulation (1.2 mA, 5 Hz, 5 ms, 5 min); the ratio (stimulated/unstimulated sides) decreased from 1.81 to 1.23, P less than 0.005). 3. GR43175 (100 micrograms kg-1, i.v., rats; 30 micrograms kg-1, guinea-pigs) decreased the leakage of radiolabelled albumin from 163% to 119% (P less than 0.005, guinea-pig) or from 174 to 118% (P less than 0.05, rat) above vehicle-treated controls when injected ten minutes before systemic capsaicin treatment (0.5 or 1 mumol kg-1, i.v.). 4. GR43175 (30-300 micrograms kg-1) did not block plasma protein extravasation within extracranial tissues of rats and guinea-pigs innervated by the trigeminal nerve (conjunctiva, eyelid and lip). 5. The protein leakage which followed the i.v. administration of 5-HT (1 mumol kg-1) or neuropeptides which mediate neurogenic plasma extravasation, substance P (0.3 nmol kg-1 or 1 nmol kg-1) and neurokinin A (1 nmol kg-1), was not blocked by GR43175 (100, 300 micrograms kg-1) despite the presence of leakage in amounts equivalent to that following neurogenic stimulation. 6. GR43175 (100 micrograms kg-1) decreased bradykinin (10 mumol kg-1)-induced extravasation from 142 to 115% above vehicle-treated animals (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Neuropeptide Y Y2 receptor-mediated attenuation of neurogenic plasma extravasation acting through pertussis toxin-sensitive mechanisms.

1. The effects of neuropeptide Y (NPY) receptor agonists (administered intravenously) were examined on plasma protein ([125I]-bovine serum albumin) leakage within dura mater evoked by unilateral trigeminal ganglion stimulation (0.6 mA, 5 ms, 5 Hz, 5 min), capsaicin (1 mumol kg-1, i.v.) or substance P (1 nmol kg-1, i.v.) in anaesthetized Sprague-Dawley rats. 2. NPY (EC50: 5.6 nmol kg-1) and NPY fragment 13-36 [NPY (13-36)] (ED50: 4.3 nmol kg-1), an NPY Y2 receptor agonist, dose-dependently attenuated [125I]-bovine serum albumin extravasation from meningeal vessels when administered 10 min prior to electrical stimulation. [Leu31, Pro34]-NPY, an NPY Y1 and Y3 receptor agonist, inhibited the response at a higher dose only (23 nmol kg-1) (P < 0.05). 3. NPY also significantly decreased plasma protein extravasation induced by capsaicin (1 mumol kg-1) but not by substance P (1 nmol kg-1). 4. Pertussis toxin (20 micrograms kg-1, administered intracisternally 48 h prior to stimulation) blocked completely the inhibitory effect of NPY and NPY (13-36) but did not inhibit extravasation alone. 5. We conclude that NPY inhibits neurogenically-mediated plasma protein extravasation acting through presynaptic pertussis toxin-sensitive NPY Y2 receptors, possibly by inhibition of neuropeptide release from perivascular trigeminovascular afferents.     

大鼠过敏性气道炎症中VCAM—1表达、嗜酸细胞浸润和药理调节

目的:探讨过敏性气道炎症大鼠肺内VCAM-1表达和嗜酸细胞浸润,以及速激肽NK-1受体拮抗剂SR140333和地塞米松的可能调节方式.方法:致敏大鼠以1％卵白蛋白气雾吸入攻击后24小时,测定VCAM-1在不同组别大鼠肺内的表达和支气管周围嗜酸细胞浸润.抗原攻击前3天,每天2次腹腔注射SR140333(0.01,0.10mg/kg)或地塞米松(0.50mg/kg).结果:与未致敏大鼠相比VCAM-1在致敏大鼠肺内表达增加(P<0.05),预先用地塞米松处理可抑制其增加(P<0.05),SR140333无此作用(P>0.05).此外,抗原攻击致敏大鼠促使支气管周围嗜酸细胞浸润,但不能进一步增加VCAM-1的表达(P>0.05).SR140333抑制嗜酸细胞浸润(P<0.05),但不影响VCAM-1表达(P>0.05);地塞米松则抑制这两种反应(P<0.05).结论:VCAM-1表达在抗原致敏后增加,地塞米松和SR140333抑制大鼠过敏性气道炎症的机制可能不同.     

The induction of a biphasic bronchospasm by the ETB agonist, IRL 1620, due to thromboxane A2 generation and endothelin-1 release in guinea-pigs.

1. IRL 1620 (0.01-0.1 mg kg-1, i.v.), a selective endothelin B (ETB) receptor agonist, induced a dose-dependent biphasic increase in total lung resistance and a decrease in dynamic compliance in anaesthetized and artificially ventilated guinea-pigs. After intravenous injection of IRL 1620 (0.03 mg kg-1), the first phase was observed within 2 min whereas the second phase started between 5 and 10 min after injection and was long lasting. 2. In order to characterize which endothelin receptors are involved in both phases of bronchoconstriction, we studied the effect of ETA and ETB receptor antagonists (BQ 123 and BQ 788, respectively). BQ 788 (0.1-1 mg kg-1, i.v.) inhibited, in a dose-dependent manner, both phases of bronchoconstriction. BQ 123 (3 mg kg-1, i.v.) markedly inhibited (by 76%) the second phase of bronchoconstriction but had no effect on the early component of the response. 3. The effect of atropine, neurokinin-I (NK1) and neurokinin-2 (NK2) receptor antagonists (SR140333 and SR48968, respectively) were tested to investigate the possible involvement of cholinergic and sensory nerve activation, respectively, in the response to IRL 1620. Likewise, the role of arachidonic acid metabolites (leukotriene D4 antagonist, ONO-1078 and thromboxane A2 (TXA2) inhibitor, OKY-046) in this response was also investigated. OKY-046 (1 mg kg-1, i.v.) and atropine (1 mg kg-1, i.v.) partially inhibited the first phase (by 80% and 20%, respectively) without affecting the late phase of bronchoconstriction. Neither ONO-1078 (1 mg kg-1, i.v.) nor the combination of SR140333 (0.2 mg kg-1, i.v.) and SR 48968 (0.2 mg kg-1, i.v.) modified IRL 1620-induced bronchoconstriction. 4. A low dose of IRL 1620 (0.005 mg kg-1, i.v.) induced a monophasic bronchoconstriction. Pretreatment by phosphoramidon (100 mumol kg-1, i.v.) restored the second phase of bronchoconstriction. In this condition, BQ 123 (3 mg kg-1, i.v.) was able to inhibit partially the second phase of bronchoconstriction. 5. These results suggest that both phases of bronchoconstriction induced by IRL 1620 were mediated primarily by ETB receptor activation, the first phase being a consequence of TXA2 and acetylcholine release. The inhibition by an ETA receptor antagonist and the restoration by a neutral endopeptidase (NEP) inhibitor of the second phase of bronchoconstriction suggests that primary activation of ETB receptors leads to autocrine/paracrine endothelin-1 (ET-1) release that would subsequently cause profound bronchoconstriction through both ETA and ETB receptor activation.     

Effects of the tripeptide substance P antagonist, FR113680, on airway constriction and airway edema induced by neurokinins in guinea-pigs.

FR113680 is a newly developed tripeptide substance P (SP) receptor antagonist. The effects of FR113680 on airway constriction and airway edema induced by neurokinins were investigated in guinea-pigs. In in vitro experiments, FR113680 inhibited the contraction of isolated guinea-pig trachea induced by SP and neurokinin A (NKA) in a dose-dependent manner with IC50 values of 2.3 x 10(-6) and 1.5 x 10(-5) M, respectively. The tracheal contraction induced by histamine and acetylcholine was not affected by FR113680. FR113680 (5 x 10(-5) M) also significantly inhibited the atropine-resistant contraction of isolated guinea-pig bronchi induced by electrical field stimulation. In in vivo experiments, FR113680 given i.v. inhibited SP-induced airway constriction in guinea-pigs at doses of 1 and 10 mg kg-1. However, FR113680 only inhibited NKA- and capsaicin-induced airway constriction by 40-50% even at a dose of 10 mg kg-1. FR113680 also inhibited SP-induced airway edema in guinea-pigs with the same potency as it inhibited SP-induced airway constriction. Histamine-induced airway constriction and airway edema were not affected at a dose of 10 mg kg-1. These results suggest that FR113680 preferentially inhibits responses induced by NK1 receptor activation (SP-induced airway constriction and airway edema), but is less effective on a NK2 receptor-induced response (airway constriction by NKA and neurogenic stimulation).