豚鼠离体气管平滑肌舒缩性压力测量法

离体气管平滑肌舒缩性的检测是许多相关实验研究所必须具备的方法。传统的检测方法主要包括有气管片法、气管环法、气管螺旋条法和气管容积法等[1～ 3] ,这些方法都分别具有操作复杂 ,灵敏度较低 ,记录曲线粗略 ,破坏气管完整性等不足 ,为克服上述缺点 ,本实验室试用测压法检测完整离体气管平滑肌舒缩功能 ,获得比较满意的结果。1　材料与方法动物用豚鼠 ,♀♂不拘 ,体重 3 5 0～ 4 5 0ｇ。击其后脑至昏 ,立即剖开颈部 ,取出 2～ 3ｃｍ完整气管段 ,放入充氧克氏液中 ,剥去外附组织 ,克氏液冲净管腔。取两根直径为 2 5～ 3 5ｍｍ的塑料管分…     

Acetamide—45抑制组胺和乙酰甲胆碱引起的豚鼠离体气管收缩

目的:探讨新型抗变态反应药N-对氟苄基-3-[(N-4-吡啶)-乙酸胺]-吲哚-45(acetamide-45)对组胺和乙酰甲胆碱引起的豚鼠离体气管收缩的影响.方法:以acetamide-45预处理气管标本后,以累积剂量法给予组胺和乙酰甲胆碱,观察acetamide-45对组胺和乙酰甲胆碱量效曲线的影响.气管张力的变化通过换能器转变为电信号并由记录仪记录.结果:Acetamide-45(1-30μmol/L)浓度依赖地抑制组胺和乙酰甲胆碱引起的豚鼠离体气管收缩.Acetamide-45(3,10,30μmol/L)使组胺的量效曲线的最大效应下降了21％—51％,使组胺的EC_(50)值(95％可信限)分别增加到31.1(24.4—39.8),34.7(26.8-45.0)和134.4(82.2-220.0)μmol/L.另一方面,acetamide-45更有效地抑制乙酰甲胆碱引起的豚鼠离体气管收缩.结论:Acetamide-45抑制由组胶和乙酰甲胆碱引起的豚鼠离体气管收缩,提示acetamide-45的抑制作用是非特异性地作用于组胺受体或胆碱能受体.     

Inhibition of antigen-induced contraction of guinea pig trachea by ICI 198,615

We examined the extent of peptide leukotrienes involvement in ovalbumin-induced contraction of guinea pig trachea isolated from animals passively sensitized with antiovalbumin antibodies. Antigen challenge resulted in a concentration-dependent (EC50 = 10 +/- 3 ng/ml, X +/- S.E.M., n = 6) and prolonged (greater than 60 min) contraction of guinea pig trachea. The maximal contractile response was directly proportional to the quantity of sensitizing antibodies. The maximal response (but not EC50 for ovalbumin) was significantly (P less than 0.01) enhanced by indomethacin (20%), only slightly (10%) inhibited by the histamine H1-antagonist pyrilamine and unaffected by the platelet-activating factor (PAF) antagonist CV-3988. The potent and selective leukotriene antagonist ICI 198,615 partially (45%) inhibited the antigen-induced contraction in a concentration-related fashion (1-300 nM). Even at concentrations that abolish responses to leukotrienes, ICI 198,615 did not further inhibit the response, nor could other leukotriene antagonists (i.e. LY 171883 or FPL 55712) inhibit more than 50% of this response. In contrast, the 5-lipoxygenase inhibitors AA-861 and REV 5901, also a leukotriene antagonist, abolished the contractile response. Taken together, the results suggest that in guinea pig trachea, leukotrienes, in combination with other lipoxygenase metabolites, mediate a major part of the response to antigen. In contrast, PAF, histamine and prostaglandins appear to play only a minor role.     

The extract from Nandina domestica THUNBERG inhibits histamine- and serotonin-induced contraction in isolated guinea pig trachea

Although the fruit of Nandina domestica THUNBERG (ND) has been used to treat respiratory disorders such as coughing and breathing difficulty in Japan for many years, very little is known about mechanisms underlying its action. In the present study, we investigated effects of the crude extract from ND (NDE) and one of its constituents, nantenine, on contractile responses in isolated guinea pig tracheal ring preparations. In normal experimental condition, guinea pig trachea remained tonically contracted during the resting state, and addition of NDE (1 mg/ml) caused a relaxation of tracheal smooth muscles, but had little effect on the responsiveness of trachea to acetylcholine. The basal, tonic contraction was abolished by the presence of atropine and indomethacin. In this condition, NDE at 0.1-1 mg/ml inhibited histamine-induced contraction in both competitive and non-competitive manners. NDE at 0.01-1 mg/ml inhibited serotonin-induced contraction in a competitive manner. Nantenine (2-20 microM) did not affect histamine-induced contraction, and slightly inhibited serotonin-induced contraction. These results suggest that NDE has inhibitory effects on tracheal smooth muscle contraction, and nantenine cannot account solely for this effect of NDE.     

Aurovertin E, a new polyene pyrone from the basidiomycete Albatrellus confluens

A new polyene pyrone, aurovertin E (2), was isolated along with aurovertin B (1) from the culture mycelia of the basidiomycete Albatrellus confluens. Their structures were elucidated on the basis of spectroscopic studies including 2D NMR experiments. This is the first example of the occurrence of aurovertins in basidiomycetes.     

Leukotriene D4 elicits a non-sustained contraction of the guinea pig trachea in calcium-free buffer

The contraction of the isolated guinea pig trachea elicited by leukotriene D4 (LTD4) in Ca2+-free buffer (containing 10(-4) M EGTA) achieved a maximum at 6-8 min and relaxed back to baseline approximately 25 min after challenge with LTD4. In contrast, LTD4 elicited a sustained contraction in the presence of 1.8 mM calcium. This sustained contraction in the presence of calcium was reproduced upon repeated LTD4 challenge, whereas in Ca2+-free buffer, only one LTD4-induced contraction could be obtained. The amplitude of the LTD4-induced contraction in Ca2+-free buffer decreased in a time-dependent manner which was also dependent upon the concentration of LTD4. At 10(-7) and 10(-6) M LTD4, small contractions (11% and 20% of control, respectively) were measured after 30 min in Ca2+-free buffer, whereas 10(-8) M LTD4 elicited a contraction at 15 min but not after 30 min in Ca2+-free buffer. Whereas washing the trachea for 5 min with LaCl3 (1.8 mM) only partially suppressed the LTD4-induced contraction in the presence of calcium, the contraction elicited by LTD4 in Ca2+-free buffer was not affected by LaCl3. The LTD4-induced contraction in Ca2+-free buffer was not affected by verapamil (10(-6) M); in contrast, the putative intracellular calcium antagonist, TMB-8 (10(-4) M), blocked the LTD4-induced contraction. These results provide evidence that the release of an intracellular calcium store plays an important role in the initiation of the LTD4-induced contraction of the guinea pig trachea. In addition, these results suggest that an extracellular calcium source may account for a small part of the LTD4-induced contraction.     

The effects of SRS-A and histamine antagonists on antigen-induced contraction of guinea pig trachea

Spirally cut tracheae from actively sensitized guinea pigs were challenged with antigen in the presence and absence of indomethacin. In the absence of indomethacin, the SRS-A antagonist FPL55712, added 30 min before challenge, had no effect on antigen-induced contraction (ATC) when added in concentrations 1.7 × 10⁻⁶ M. However with the highest concentration employed (5.2 × 10⁻⁶M) the duration of ATC was reduced by 45%. Furthermore the enhancement by indomethacin of the peak height of ATC was reduced even by lower (5.2 × 10⁻⁷M) concentrations of FPL55712. The inhibition by FPL55712 was time-dependent, suggesting that its action was not confined to competitive receptor antagonism. Hence, although our previous data indicate that a lipoxygenase product is involved in ATC, the current findings suggest that lipoxygenase products in addition to SRS-A contribute to the response. The H₁-antagonists mepyramine, chlorpheniramine and diphenhydramine inhibited ATC only in the first minute, and the peak height was reduced only by diphenyhydramine. The H₂-antagonist cimetidine had no effect on ATC. These data suggest that the contribution of histamine to ATC is small, confined to the first minute following antigen challenge and mediated via H₁-receptors. Reduction of the peak height by diphenyhydramine may be unrelated to its H₁-antagonist properties.     

Antigen-induced sulfidopeptide leukotriene release from the guinea pig superfused trachea

The effect of antigen (ovalbumin) challenge on smooth muscle contraction and release of sulfidopeptide leukotrienes and histamine from superfused, actively sensitized guinea pig trachea was examined. Maximum concentrations of ovalbumin caused the release of 16 +/- 4 ng/g immunoreactive sulfidopeptide leukotriene (i-LT) and 27 +/- 3% of the endogenous histamine (x +/- S.E.M., n = 19). High performance liquid chromatography combined with a sulfidopeptide leukotriene radioimmunoassay was used to demonstrate that on a molar basis, approximately 10% of the leukotriene immunoreactivity recovered was LTC4, 45% LTD4 and 45% LTE4. Indomethacin slightly increased ovalbumin-induced histamine release and substantially enhanced (3-fold) i-LT release from the trachea. Neither the profile nor rate of sulfidopeptide leukotriene release was altered by indomethacin. Indomethacin had no effect on the maximum amplitude of the antigen-induced contraction but significantly enhanced the magnitude of contraction observed after 10 min of antigen exposure. These results demonstrate that actively sensitized airways synthesize and release sulfidopeptide leukotrienes upon challenge with specific antigen and that endogenously formed LTC4 is efficiently metabolized to LTD4 and LTE4. The results with indomethacin support the hypothesis that indomethacin potentiates antigen-induced airway contraction in vitro by enhancing the release of mast cell associated mediators.     

One new ergostane-type steroid and three new phthalide derivatives from cultures of the basidiomycete Albatrellus confluens

One new ergostane-type steroid, (12β,15β,22R,23S,24S)-22,25-epoxy-12,15,23-trihydroxyergost-4,6,8(14)-trien-3-one (1), three new phthalide derivatives, 5-(2′,3′-epoxy-3′,3′-dimethylpropoxy)-7-methoxy-6-methylphthalide (2), (2′)-(Z)-5-(3′-hydroxymethyl-3′-methylallyloxy)-7-methoxy-6-methylphthalide (3), and 5-(3′,3′-dimethylallyloxy)-7-hydroxy-6-methylphthalide (4), along with one known phthalide derivative, 5-(3′,3′-dimethylallyloxy)-7-methoxy-6-methylphthalide (5), were isolated from cultures of the basidiomycete Albatrellus confluens. The structures of the new compounds were established on the basis of extensive spectroscopic data (IR, MS, 1D, and 2D NMR) analyses. All compounds were evaluated for their cytotoxic activities on five tumor cell lines.     

Effects of albaconol from the basidiomycete Albatrellus confluens on DNA topoisomerase II-mediated DNA cleavage and relaxation

The effect of albaconol on the growth of human tumor cell, DNA topoisomerase (topo)-mediated DNA cleavage and direct DNA breakage was investigated. Albaconol inhibited significantly the growth of the human tumor cell lines K562, A549, BGC-823 and Bcap-37, the IC5s values were 7.99 +/- 0.4, 3.17 +/- 0.89, 4.18 +/- 0.14 and 7.45 +/- 2.5 microM, respectively. Albaconol stabilized and increased the topo 11-mediated DNA cleavable complex and inhibited the religation activity of topo II in a dose-dependent manner, but it failed to affect the activity of topo I. Albaconol directly broke pBR322 DNA at high concentrations, but there was no effect on the macromolecule of K562 cells. These results strongly suggest that albaconol targeted specifically to DNA topo II and that this is one of the mechanisms of its antitumor action; the direct action of albaconol on DNA may partly contribute to its anti-tumor activity at high concentrations.     

多沙唑嗪对映体对豚鼠离体气管环的作用

目的:研究R-多沙唑嗪(R-doxazosin,R-DOX)、S-多沙唑嗪(S-doxazosin,S-DOX)和rac-多沙唑嗪(rac-doxazosin,rac-DOX)对豚鼠离体气管环的作用.方法:采用豚鼠离体气管环,观察DOX对映体对离体气管环静息张力、卡巴胆碱诱发收缩反应以及异丙肾上腺素诱发舒张反应的影响.结果:10和30ìmol·L-1 DOX对映体对豚鼠离体气管环静患张力无显著性影响(P>0.05).S-DOX 10 ìmol·L-1使卡巴胆碱诱发豚鼠离体气管环收缩反应的Emax明显增大(P<0.05),但卡巴胆碱的EC50未发生明显改变.相反,同浓度R-DOX明显降低卡巴胆碱诱发的豚鼠离体气管环收缩反应的Emax(P<0.05),但使卡巴胆碱的EC50明显减小.S-DOX 10ìmol·L-1明显抑制异丙肾上腺素诱发的豚鼠离体气管环舒张反应量效曲线,并使异丙肾上腺素的EC50明显增大(P<0.05).R-DOX,rac-DOX和s-DOX 30 ìmol·L-1均不影响异丙肾上腺素的舒张反应量效曲线.结论:在豚鼠离体气管环标本S-DOX使卡巴胆碱诱发收缩反应的Emax明显增大,且明显抑制异丙肾上腺素的舒张反应.     

Effects of anti-asthma drugs and potassium channel openers on neurally-mediated contraction of isolated guinea pig trachea.

The effects of anti-asthma drugs, isoproterenol, aminophylline and hydrocortisone, and potassium channel openers on the contraction induced by electrical stimulation or exogenously applied acetylcholine were investigated in isolated guinea pig trachea. Isoproterenol and aminophylline non-selectively inhibited both the contraction evoked by vagus nerve- and that by transmural field-stimulation, but had no effect on the response induced by exogenously applied acetylcholine. Hydrocortisone and potassium channel openers, NIP-121 and cromakalim, preferentially inhibited vagus nerve-mediated response. These results suggest that anti-asthma drugs may have an ability to inhibit neurally-mediated contraction in the guinea pig trachea.     

苄基四氢巴马汀及己吡氰胍对豚鼠气管及心肌的作用

本实验表明.在豚鼠左心房,苄基四氢巴马汀(BTHP)表现为正性肌力作用,而己吡氰胍(pinacidil)则表现为负性肌力作用。但二者均可抑制肾上腺素所诱发的自律性。在气管,BTHP可使乙酰胆碱(Ach)及组胺(histamine)致气管收缩的量效曲线左移.其左移程度以低剂量时最为明显.与此相反。己吡氰胍则使Ach及组胺的量效曲线右移.最大反应基本不变。当苄基四氢巴马汀与己吡氰胍同时存在时,则Ach及组胺的量效曲线基本不变.提示二药可能作用于气管的同一部位。     

Autoinhibition and desensitization of serotonergic responses in guinea pig ileum

The present study was undertaken to investigate the autoinhibition and desensitization of 5-hydroxytryptamine (5-HT) using another agonist MK-212 on guinea pig ileum. 5-HT and MK-212 produced dose dependent contractions of guinea pig ileum. The responses to MK-212 were reduced in the presence of 5-HT and vice versa. Neither 5-HT nor MK-212 produced any change in the responses to histamine, acetylcholine or KCl. Increase in Ca++ in bathing fluid reversed the desensitization produced by MK-212 or 5-HT. Our data suggest that 5-HT and MK-212 produce desensitization which is specific for serotonergic receptors and possibly involves Ca++ ions.     

Bradykinin-induced contraction of guinea pig lung in vitro

We have investigated the contractile effect of bradykinin (BK) in guinea pig lung in vitro. BK induces a dose-related contraction of lung parenchymal strips which is increased significantly in the presence of 10^–5 M captopril (an angiotensin converting enzyme inhibitor) or 10^–5 M dl-thiorphan (a neutral endopeptidase inhibitor). The kininase I inhibitor, dl-2-mercaptomethyl-3-guanidino-ethylthiopropionic acid (MGTPA), has no effect on the BK-induced contraction. BK is more potent in contracting parenchymal lung strips than other contractile agents (histamine, carbachol and substance P), however the BK-induced maximal contraction is lower than those obtained with histamine and carbachol. The B₁ agonist, des-Arg⁹-BK, does not contract lung parenchymal strips. The new BK B₂ receptor antagonists (Hoe 140, NPC 17731 and NPC 17761), which possess binding affinities in the nanomolar range, inhibit the BK-induced contractile response in a dose-dependent manner. The BK-induced contraction was unaffected by propranolol, atropine, tetrodotoxin, capsaicin pre-treatment, triprolidine, methysergide, Ro 19-3704 and N-nitro-l-arginine-methyl-ester (l-NAME), excluding the involvement of nervous pathways, preformed mast cell mediators, platelet-activating factor and nitric oxide. However, indomethacin, a cyclooxygenase inhibitor, AA-861, a 5-lipoxygenase inhibitor, and furegrelate, a thromboxane A₂ synthase inhibitor, decreased the contractile response to BK, suggesting that both cyclooxygenase and 5-lipoxygenase products are involved in this contraction. Thapsigargin, an inhibitor of the endoplasmic reticulum Ca²⁺ ATPase, abolished the BK-induced contraction demonstrating an intracellular calcium-dependent mechanism. Moreover, on a mixed lung cell suspension, obtained by enzymatic digestion, BK is able to induce phosphoinositide production. We conclude that BK, acting on B2 receptors, is a powerful contractile agent of the guinea pig lung in vitro. The BK-induced contraction, modulated by kininases II, is not dependent on neural mechanisms whereas both eicosanoids and intracellular calcium are involved. Correspondence to: J. P. Gies at the above address     

Hyperosmolarity-induced relaxation and prostaglandin release in guinea pig trachea in vitro

In this study, a tracheal perfusion apparatus was used to investigate the nature of the relaxing factor released by hyperosmolarity on the epithelial side of guinea pig trachea. NaCl induced concentration-dependent relaxation. This relaxation was not affected when the trachea was preincubated with a vasoactive intestinal peptide (VIP) receptor antagonist or with the nitric oxide synthesis inhibitor N(G)-monomethyl-L-arginine (L-NMMA). When the prostaglandin synthesis was prevented by preincubation with the phospholipase A(2)-inhibitor quinacrine, or the cyclooxygenase inhibitor indomethacin, the maximal relaxation induced by NaCl was suppressed by 50% (P<0.05). Moreover, the prostaglandin E(2) concentration was four times higher (P<0.05) in the organ bath during the relaxations, whereas the nitric oxide concentration remained unchanged. In conclusion, increased osmolarity on the airway surface leads to the release of prostaglandins, which are involved in part in the hyperosmolarity-induced relaxation of airway smooth muscle. This might be relevant for asthmatic patients since prostaglandin may modulate the bronchoconstrictive response to hyperosmolar stimuli and exercise.     

Can the epithelium affect allergen-evoked histamine release from the perfused guinea pig trachea?

The aim of this study was to investigate the influence of the epithelium on allergen-evoked histamine release. Isolated tracheal preparations from guinea-pigs, with the epithelium either left intact or removed, were used. The trachea was perfused and challenged with egg-albumin (EA) either extra- or intraluminally. Fractions of the perfusate were collected for analysis of the histamine and EA contents. When EA was added intraluminally and the epithelium was removed, a marked peak in histamine release could be detected. In the presence of intact epithelium there was no marked histamine peak. EA added extraluminally gave the same results but the histamine peak was less pronounced. The epithelium apparently acts as a barrier, the nature of which remains to be elucidated.     

扎普司特和谷胱甘肽翻转豚鼠离体气管对硝普钠的耐受性

上皮完整或去上皮的豚鼠离体气管以３００μｍｏｌ·Ｌ－１硝普钠（ＳＮＰ）预处理１ｈ，使ＳＮＰ对抗乙醋甲胆碱气管收缩作用的剂量反应曲线右移１．３－１．５倍，最大舒张率下降４１％－５８％，形成ＳＮＰ气管松弛作用的耐受性．８－溴环鸟苷酸可模拟ＳＮＰ在豚鼠离体气管形成的ＳＮＰ耐受性，谷胱甘肽（１ｍｍｏｌ·Ｌ－１）及环核苷酸磷酸二酯酶（ＰＤＥ）Ⅴ抑制剂扎普司特（３０μｍｏｌ·Ｌ－１）均可部分翻转ＳＮＰ的气管松弛作用耐受性，而蛋白合成抑制剂环己酰亚胺（１０μｍｏｌ·Ｌ－１）对ＳＮＰ的耐受性无预防作用．结果表明ＳＮＰ可产生豚鼠离体气管松弛耐受性，这可能是由于气管平滑肌中环鸟苷酸（ｃＧＭＰ）积聚而下调鸟苷酸环化酶（ＧＣ）活性和上调ＰＤＥⅤ活性．