嘌呤拟似物对豚鼠胃窦环行肌自发性收缩及电活动的影响

为探讨非肾上腺素能非胆碱能神经递质对胃窦环行肌功能的调节作用,在离体胃平滑肌上观察了嘌呤拟似物对胃窦环行肌自发性收缩活动和电活动的影响。电活动用传统的细胞内微电极记录,并和收缩活动同步描记于多道生理记录仪。结果表明,嘌呤能P2Y受体激动剂,三磷酸腺苷(ATP)和2-methylthio ATP(2-MeSATP)均增强胃窦平滑肌的收缩活动,但不影响电活动,而且ATP和2-MeSATP对胃平滑肌收缩活动的增强作用可被嘌呤能P2Y受体阻断剂,reactive blue-2和苏拉明(suramin)所阻断。用100μmol／L α,β-MeATP引起的脱敏感使P2X受体被阻断,ATP增强胃窦平滑肌收缩活动的效应不受影响。嘌呤能P2X受体激动剂,α,β-MeATP明显抑制胃窦环行肌自发性收缩活动,同时使膜电位明显超极化。ATP对胃窦平滑肌的收缩作用不被L型钙通道阻断剂尼卡地平(nicardipine)阻断,但细胞外用无钙液灌流时这种效应则完全被阻断。用前列腺素合成抑制剂消炎痛预先处理20min后,ATP和2-MeSATP仍能增强胃窦平滑肌的自发性收缩活动。以上结果提示：(1)ATP和2-MeSATP通过嘌呤能P2Y受体增强胃窦平滑肌的自发性收缩活动,而α,β-MeATP或β,γ-MeATP通过嘌呤能P2X受体使膜电位超极化,引起胃窦平滑肌的舒张;(2)ATP和2-MeSATP增强胃窦平滑肌自发性收缩活动的效应依赖于细胞外钙,但钙离子进入细胞的途径并不是电压依赖性钙通道;(3)ATP和2-MeSATP增强胃窦平滑肌自发性收缩活动的效应不通过前列腺素介导。     

P物质对大鼠胃窦肌条收缩活动的影响及其机制探讨

本文利用器官浴槽孵育离体大鼠胃窦肌条,观察Ｐ物质（ｓｕｂｓｔａｎｃｅＰ,ＳＰ）对肌条收缩的效应及多种拮抗剂或抑制剂对ＳＰ效应的影响。结果：（１）ＳＰ明显增强肌条收缩幅度,在剂量为８×１０－１１－８×１０－７ｍｏｌ范围内里剂量－效应关系。ＳＰ４×１０－８ｍｏｌ,使肌条收缩幅度增强１６０．９±２３．０％．与生理盐水组比较Ｐ＜０．００１。（２）神经节阻断剂六烃季胺、５－ＨＴ２受体阻断剂赛庚啶、Ｈ１受体阻断剂苯海拉明、磷酸二酯酶抑制剂氨茶碱使ＳＰ肌条收缩幅度增强效应明显减弱（Ｐ＜０．０５）。（３）阿托品、心得安、酚妥拉明、氟哌啶醇和纳洛酮预孵育后,ＳＰ增强收缩幅度的效应与单独ＳＰ组相比差异无显著性。结果提示ＳＰ可能是肠神经系统中的非胆碱能兴奋性递质,可能通过激活５－ＨＴ神经元、促使组织胺释放等途径而增强肌条的收缩幅度。     

不同牵张刺激对豚鼠胃窦环行肌细胞电压依赖性钙电流的影响

利用全细胞膜片钳技术,在胃窦环行肌细胞上观察了不同方式的牵张刺激对电压依赖性钙电流的影响,探讨牵张刺激对胃窦平滑肌细胞电压依赖性钙电流的作用。用低渗性溶液灌流细胞引起的牵张刺激首先增加电压依赖性钙电流,接着激活一种内向性钳制电流。钙电流的增加发生在灌流后１ｍｉｎ内,而内向性钳制电流在细胞明显膨胀之后缓慢激活。低渗和正压引起的细胞膨胀明显增加电压依赖性钙离子电流,而利用两个电极直接牵细胞则不出现钙电     

吗啡和纳洛酮对豚鼠离体胆囊肌条活动的作用

5种浓度的吗啡对胆囊肌条的自动节律性收缩,均有明显加强作用。阿片受体拮抗剂——纳洛酮可阻断和翻转吗啡对胆囊肌条的作用,说明豚鼠的胆囊壁有阿片受体。乙酰胆碱显著地加强胆囊肌条的收缩,此效应可被阿托品阻断,而且阿托品也使吗啡对胆囊肌条的作用明显减弱。异丙肾上腺素和去甲肾上腺素分别抑制和加强胆囊肌条的运动,前者的效应可被心得宁阻断,后者则被酚妥拉明阻断,但两者的效应均不受纳洛酮的影响。而心得宁和酚妥拉明不影响吗啡对胆囊肌条的作用。本实验似能表明,吗啡对胆囊肌条运动的调节是通过阿片受体而起作用的。但吗啡对胆囊肌条的作用与肾上腺素能α和β受体无关。     

烟碱和槟榔碱对离体大鼠海马脑片CA_1锥体细胞外诱发电位的影响

在离体Ｗｉｓｔａｒ大鼠海马脑片上,用微电极记录刺激顶树突层Ｓｃｈａｆｆｅｒ侧支引起的ＣＡ＿１区锥体细胞外群峰电位（ＰＳ）。观察用半浸式浴槽或多管微电极气压微量注射给予Ｎ受体激动剂烟碱（Ｎｉｃ）和Ｍ受体激动剂槟榔碱（Ａｒｅ）对ＰＳ的影响,探讨Ｍ和Ｎ受体功能。结果表明：Ｎｉｃ对ＰＳ幅度无明显影响,浓度１．０ｍｍｏｌ／Ｌ时约１／４脑片诱发出第二个群峰电位（ＰＳ＿２）,浓度增加,ＰＳ＿２发生率增加,ＰＳ＿２幅度较ＰＳ低。美加明能部分对抗烟碱诱发的ＰＳ＿２,表明ＰＳ＿２出现与Ｎ受休关系密切。Ａｒｅ降低ＰＳ幅度,当浓度达到０．００１ｍｍｏｌ／Ｌ即能使ＰＳ幅度降低为正常的７４％,ＰＳ幅度降低存在有效量关系,低浓度阿托品能选择性地对抗之,表明Ａｒｅ所致ＰＳ幅度下降是通过兴奋Ｍ受体的结果。     

烟碱和槟榔碱对离体大鼠海马脑片CA1锥体细胞外诱发电位…

在离全Ｗｉｓｔａｒ大鼠海马脑片上,用微电极记录刺激顶树突层Ｓｃｈａｆｆｅｒ侧支引起的ＣＡ１区锥体细胞外群峰电位（ＰＳ）。观察用半浸式浴槽或多管微电极气压微量注射给予Ｎ受体激动剂烟碱（Ｎｉｃ）和Ｍ受体激动剂槟碱（Ａｒｅ）对ＰＳ的影响,探讨Ｍ和Ｎ受体功能。结果表明：Ｎｉｃ对ＰＳ幅度无明显影响,浓度过．０ｍｍｏｌ／Ｌ时约１／４脑片诱发出第二个群峰电位（ＰＳ２）,浓度增加,ＰＳ２发生率增加,ＰＳ２幅度较Ｐ     

前列腺素E1对大鼠胃窦肌电活动的影响

用慢性实验方法,在３０只Ｗｉｓｔａｒ大鼠胃窦部浆膜面埋置Ａｇ／ＡｇＣｌ双极电极,观察腹腔注射前列腺素Ｅ１（ｐｒｏｓｔａｇｌａｎｄｉｎＥ１,ＰＧＥ１）对胃窦肌电活动的影响。     

脑啡肽对离体动脉条收缩活动的影响及其机制分析

亮氨酸脑啡肽(L-ENK)和甲硫氨酸脑啡肽(M-ENK)对兔耳动脉条在电场刺激下所产生的收缩反应具有抑制作用,此抑制效应具有剂量依赖关系,并且可以被阿片受体阻断剂纳洛酮阻断。用荧光法测定动脉条去甲肾上腺素(NE)释放量的实验表明,脑啡肽(ENK)是通过抑制支配动脉壁交感神经末梢释放NE,继而抑制血管平滑肌收缩的。实验还证明,吗啡对动脉条的收缩无抑制作用,从而表明在兔耳动脉上以δ亚型阿片受体为主,可能无μ亚型阿片受体。可卡因和育亨宾通过不同的作用途径使动脉条释放NE增加。     

钙离子在激动剂引起豚鼠胆囊肌条收缩中的作用

本工作采用肌肉等张收缩记录法和 cGMP、cAMP 的放射免疫测定法,来研究乙酰胆碱、碳酰胆碱和胃肠激素(雨蛙肽)引起豚鼠胆囊肌条(GBMS)收缩中 Ca~(2+)的作用。结果表明,在有钙液中 GBMS 收缩较无钙液中强。在无钙液、在 EDTA-零钙液或异搏定-Krebs液中,GBMS 对激动剂的收缩反应降低到对照组的30%左右(P<0.01)。异搏定使碳酰胆碱刺激的 GBMS 内 cGMP 和 CAMP 含量降低(P<0.01或0.05)。这些结果提示,在激动剂引起胆囊肌条收缩中,细胞内、外钙离子均参与作用,从而影响胆囊肌条收缩。     

槟榔碱对人乳腺癌MCF-7细胞增殖和凋亡的影响

目的：观察槟榔碱对人乳腺癌细胞（MCF-7）增殖和凋亡的影响,并探讨其机制。方法：采用四甲基偶氮唑盐（MTT）法检测不同浓度（0、10、30、50、100、300、500μmol/L）槟榔碱对MCF-7细胞增殖的影响,Hoechst 33342染色和流式细胞术检测细胞凋亡,Western blot法检测Bax,Bcl-2和P53蛋白表达。结果：低浓度（0、10、30、50μmol/L）槟榔碱不影响细胞的增殖和凋亡;而高浓度（100、300、500 μmol/L）槟榔碱呈浓度依赖性抑制MCF-7细胞增殖、诱导MCF-7细胞凋亡、提高P53和Bax蛋白表达、降低Bcl-2蛋白表达。结论：高浓度槟榔碱抑制MCF-7细胞增殖、诱导凋亡,其机制可能与提高P53和Bax蛋白表达,降低Bcl-2蛋白表达有关。     

栀子对兔胃平滑肌体外运动的影响

目的：观察利胆药物-栀子对兔离体胃平滑肌的影响,并初步探讨其作用机制。方法：取兔胃肌条,安置在各恒温灌流肌槽中并用BL-310生物技能实验系统记录胃各部平滑肌条的收缩活动,结果：栀子显著升高兔胃底和胃体纵行肌条张力,增加其收缩频率,减小胃体收缩波平均振幅,并有剂量依赖关系。结论：栀子对胃肌条收缩活动具有明显的兴奋作用,这种兴奋作用部分经由M受体介导。     

Endogenous prostaglandins regulate spontaneous contractile activity of uterine strips isolated from non-pregnant pigs

Myometrial strips isolated from non-pregnant pigs show spontaneous contractile activity. In the present study, the involvement of endogenous prostaglandins in regulation of uterine spontaneous contraction was investigated using mechanical, immunohistochemical and biochemical approaches. Immunohistochemical study and Western blot analysis for immunoreactive cyclooxygenase (COX) indicated that COX-1 but not COX-2 was expressed predominantly in the myometrium of non-pregnant pigs in a muscle layer-dependent manner (longitudinal muscle>circular muscle). Pretreatment of uterine strips with indomethacin and selective COX-1 inhibitors (SC-560 and FR122047) significantly reduced both the amplitude and frequency of spontaneous contraction in the longitudinal muscle, but inhibition by COX inhibitors was negligible in the circular muscle. On the other hand, CAY10404, a COX-2 inhibitor, did not change the spontaneous contraction in either of the muscle layers. Pretreatment with SC-560 reduced myometrial PGF(2alpha) and PGE(2) levels. Contractile FP and EP(3) receptors were expressed in a muscle layer-dependent manner (longitudinal muscle>circular muscle), similar to the expression pattern of COX-1. In conclusion, endogenous prostaglandins produced by COX-1 regulate spontaneous contractile activity of non-pregnant porcine uterine longitudinal muscle selectively due to the heterogeneous expression of contractile prostanoid receptors and COX-1.     

辣椒素对离体大鼠胃平滑肌收缩性的影响

目的:考察辣椒素对离体大鼠胃平滑肌收缩性的影响。方法:本研究以大鼠的离体胃平滑肌条为模型,首先考察在正常钙克氏液、高钙克氏液和低钙克氏液中辣椒素对胃平滑肌收缩作用的影响。然后正常克氏液中,分别观察辣椒素对乙酰胆碱、新斯的明、阿托品分别存在下的胃平滑肌收缩性的影响。结果:辣椒素在2.5μmol/L-40μmol/L浓度范围内可剂量依赖性显著抑制高钙溶液(Ca2 终浓度5μmol/L)引起的大鼠胃平滑肌强烈收缩,在5μmol/L-40μmol/L浓度范围内可显著抑制正常克氏液中大鼠胃平滑肌条的运动,且具有明显剂量依赖性,在10μmol/L-40μmol/L浓度范围内可显著抑制低钙克氏液中大鼠胃平滑肌条的运动,且具有剂量依赖性。辣椒素(10μmol/L)可拮抗乙酰胆碱和新斯的明引起的收缩作用(P<0.01)。辣椒素(10μmol/L)的作用与阿托品具有相加作用(P<0.01)。结论:辣椒素对胃平滑肌的收缩具有明显的抑制作用。     

大鼠胃纵行和环行平滑肌对细胞外核苷引起的差异收缩反应

目的：观察几种细胞外核苷如ATP、urIP和四磷酸脲腺苷（Up4A）在胃纵行平滑肌（Ⅲ）和胃环行平滑肌（CM）中引起不同的反应,P2X和P2Y受体拮抗剂以及环氧合酶抑制剂五磷酸二肌苷（11＇5I）、苏拉明（suramin）和吲哚美辛对№A在删和CM中引起的收缩的影响。方法：取大鼠全胃,分离LM和CM,使用organbath系统测量平滑肌收缩。结果：Up4A可以在I_aM和CM中引起与ATP和U1P类似的收缩;IP5I对LM和CM中由Up4A引起的收缩并无影响;但suramin和吲哚美辛则能在CaM中显著抑制由Up4A引起的收缩,而LM中无此现象。结论：两种胃平滑肌对核苷类药物及其抑制剂的反应有差异。     

葡萄籽中原花青素对实验动物主动脉收缩和血小板聚集的影响

目的:研究葡萄籽中原花青素(PA)对大鼠离体主动脉平滑肌收缩活动和兔血小板聚集的影响.方法:采用大鼠离体主动脉环灌流方法,记录主动脉环张力变化,观察PA对去甲肾上腺素(NA)和KCl预收缩大鼠离体主动脉平滑肌收缩反应的舒张作用以及对NA量效曲线的影响.比浊法测定兔血小板聚集.结果:PA能明显抑制NA(10-6mol/L)预收缩大鼠离体主动脉环的反应,使NA量效曲线压低,最大反应降低,此作用无内皮依赖性,但对KCl预收缩主动脉环的舒张作用无明显影响,也不影响花生四烯酸(AA),ADP和胶原(collagen)蛋白诱导的兔血小板聚集.结论:PA能对抗NA而不影响KCl诱导的大鼠离体主动脉平滑肌的收缩,不影响兔血小板聚集.     

The effect of the Fusarium metabolite beauvericin on electromechanical and -physiological properties in isolated smooth and heart muscle preparations of guinea pigs

The electromechanical and -physiological effects of beauvericin were studied in isolated smooth and heart muscle preparations of the guinea pig. Beauvericin concentration-dependently decreased the force of contraction in precontracted (60 mM KCl) terminal ilea with an IC₅₀ of 0.86 M, and in electrically stimulated (1 Hz) papillary muscles with an IC₅₀ of 18 M. This negative inotropic effect in papillary muscles was antagonised in a non-competitive way by increased extracellular calcium concentrations. Spontaneous activity in right atria was affected at concentrations >10 M beauvericin. The negative chronotropic effect was less pronounced than the negative inotropic effect. In action potentials of electrically driven (1 Hz) papillary muscles, 10 M beauvericin significantly decreased membrane resting potential until unexcitability of the preparation occurred. Despite depolarisation of the membrane the maximum rate of rise of the action potential was not changed. The action potential duration was shortened, but the decrease was only significant at times to 20% and 50% repolarisation. These data, derived from the electrophysiological experiments, not only imply an effect on the calcium current as suggested by the effects on contractility, but also an interaction with the sodium inward and potassium outward currents.This revised version was published online in October 2005 with corrections to the Cover Date.     

Rapid inhibitory effect of glucocorticoids on airway smooth muscle contractions in guinea pigs

The common disease asthma is characterized by the obstruction, inflammation and increased sensitivity of the airways. Glucocorticoids (GCs) are one of the most potent anti-inflammatory agents available for treating allergic disease. In this study, we report that the GC budesonide (BUD) can rapidly inhibit the histamine-induced contractions of airway smooth muscle in a process mediated by non-genomic mechanisms. The tracheas of albino Hartley guinea pigs were used. We measured the effects of BUD on the increased isometric tension of trachea segment rings and the shrinking of single airway smooth muscle cells (ASMCs) induced by histamine. With the application of each reagent, the changes in the isometric tension of the segment rings upon maximum contraction and at four time points were recorded. We found that BUD significantly suppressed the increase in isometric tension induced by histamine in guinea pigs within 15 min. We also observed that BUD can reduce the histamine-induced shrinking of single ASMCs in an even shorter time. Mifepristone (RU486) and actidione did not depress the inhibitory effect of BUD. The results preclude action via genomic-mediated responses that usually take several hours to occur. We conclude therefore that GCs have a rapid non-genomic inhibitory effect on guinea pig airway smooth muscle contractions, and provide a new way to investigate this non-genomic mechanism. Further study can provide theoretical evidence for the clinical application of GCs in asthma and other allergic diseases.