可乐定镇痛与中枢Ca~(2+)的关系

用大鼠甩尾法和放射配基结合实验,探讨了可乐定镇痛与中枢Ca~(2+)的关系。CaCl_2(1μmol/rat,icv)和EGTA(0.2μmol/rat,icv)分别拮抗和增强可乐定(1mg/kg,sc)的镇痛。戊脉安(0.1μmol/rat,icy)对可乐定(1 mg/kg,sc)镇痛无明显影响,但可部分翻转CaCl_2对可乐定镇痛的拮抗。CaCl_2(1×10~(-3)mol)对[~3H]-可乐定结合无明显抑制。结果表明可乐定镇痛与脑室周围组织中Ca~(2+)浓度变化密切相关,Ca~(2+)至少部分需经对戊脉安敏感的钙通道进入细胞内方可拮抗可乐定镇痛。推沦:可乐定镇痛与神经元内Ca~(2+)有关。     

四肽FMRFa对大鼠心室肌Na+/Ca2+交换的抑制

目的　研究四肽FMRFa对大鼠单个心室肌细胞Na⁺/Ca²⁺交换的作用。方法　用膜片钳全细胞记录法测定成年大鼠心室肌细胞Na⁺/Ca²⁺交换电流(I_Na⁺/Ca²⁺)和其他离子通道电流。结果　FMRFa对大鼠心室肌细胞I_Na⁺/Ca²⁺呈浓度依赖性抑制,100μmol·L^-1浓度时抑制内向和外向I_Na⁺/Ca²⁺密度分别达60.1%和56.5%,对内向电流及外向电流的IC₅₀分别为20μmol·L^-1和34μmol·L^-1。FMRFa5μmol·L^-1抑制I_Na⁺/Ca²⁺内向和外向电流密度分别为38.7%和34.9%,但FMRFa5μmol·L^-1及20μmol·L^-1对L型钙电流、钠电流、瞬时外向电流和内向整流钾电流均无显著抑制作用。结论　FMRFa对大鼠心室肌细胞是一个特异性Na⁺/Ca²⁺交换抑制剂。     

赛庚啶对离体犬心肌肌质网Ca2+,Mg2+—ATP酶活性和45Ca2+摄取功能的影响

当赛庚啶浓度在8×10^-6mol/L～2×10^-4mol/L之间时,该药对正常犬心肌肌质网Ca²⁺,Mg²⁺—ATP酶活性几乎没有影响,仅在10^-3mol/L时对该酶活性才有一定的抑制作用(抑制率为39.85%,P<0.01)。正常犬心肌肌质网的⁴⁵Ca²⁺摄取过程有明显的时间依赖性,至第30 min,其⁴⁵Ca²⁺摄取量可达312.79±22.25 nmol/mg protein.赛庚啶对心肌肌质网的~(45)Ca²⁺摄取有一定的抑制作用,其IC₅₀为1.94×10^-4mol/L。     

1,6-二(4-苯乙基-1-甲基-1-哌嗪基)己烷二溴化物镇痛作用及机制探讨

目的　研究哌嗪类新化合物1,6-二( 4-苯乙基1-甲基-1-哌嗪基)己烷二溴化物(97-9-G4)的镇痛作用及机制。方法　扭体法、热板法研究镇痛活性;联合给药观察纳洛酮、利血平、阿托品、CaCl₂和EDTA等对97-9G4镇痛作用的影响;并测定97-9-G4对小鼠体内PGE₂的影响。结果　sc 97-9-G4 5mg/kg即可有效抑制小鼠扭体反应(P<0.05) ;sc 40mg/kg和icv 2.5μg/kg均可明显延长热板实验的舔足阈(P<0.05) ;纳洛酮、CaCl₂和EDTA均可拮抗、减弱或加强其镇痛作用;利血平、阿托品对97-9-G4的镇痛作用影响不明显。结论　97-9-G4具有明显的镇痛活性,其镇痛作用与阿片受体及体内Ca²⁺等因素有一定关系。     

神经肽DGAVP和Org2766对神经细胞内游离Ca2+的影响

运用Ca²⁺指示剂Fura-2作为细胞内钙离子的荧光探针,利用AR—CM—MIC阳离子测定系统,检测了分离的神经细胞内游离钙及其变化,并观测了DGAVP和Org2766对蛋白质合成抑制剂茴香霉素(ANI)引起细胞内钙离子浓度([Ca²⁺]_i)变化的影响。结果表明茴香霉素可使[Ca²⁺]_i显著升高,且有量效关系;DGAVP本身并不引起[Ca²⁺]_i发生显著变化,但适当剂量的DGAVP可显著对抗一定剂量范围内ANI升高[Ca²⁺]_i的作用,提示DGAVP对抗ANI的蛋白质合成抑制效应可能是通过拮抗ANI升高[Ca²⁺]_i这一途径实现的,另一神经肽Org2766则可能不是通过这一机制发生作用。从细胞内Ca²⁺的角度看,这两种肽的作用机理显然是不同的。     

环维黄杨星D对分离大鼠心室肌细胞内Ca2+和L型钙电流的影响

目的研究环维黄杨星D（CD）对大鼠心室肌细胞内Ca²⁺动员和L型钙电流(I_{Ca-L/sub>)的影响。方法采用全细胞膜片钳和激光扫描共聚焦显微术研究CD对心肌细胞ICa-L/sub>以及氯化钾、咖啡因诱发心肌细胞内Ca²⁺动员的影响。结果CD浓度依赖性抑制ICa-L/sub>。指令电压为10 mV时，1和10 μmol·L^-1 CD分别使ICa-L/sub>电流密度从（-9.9±1.8）pA/pF降至（-6.4±1.4）pA/pF和（-4.2±0.6）pA/pF。共聚焦实验显示1和10 μmol·L^-1 CD不影响静息心肌细胞［Ca²⁺］i?/sub>，对氯化钾诱发［Ca²⁺］i?/sub>升高水平无明显抑制作用；咖啡因引起的细胞内Ca²⁺动员可被CD进一步增强。结论CD浓度依赖性抑制大鼠心室肌细胞ICa-L/sub>，并有促进咖啡因诱发心肌细胞内Ca²⁺释放的作用。}     

银杏叶提取物对低氧复氧、H2O2和谷氨酸损伤时谷氨酸引起的大鼠星形胶质细胞［Ca2+］i变化的影响

目的研究银杏叶提取物对低氧复氧、H₂O₂和L-谷氨酸损伤时谷氨酸升高大鼠星形胶质细胞［Ca²⁺］_i的影响。方法钙荧光探针Fluo-3/AM标记胞浆内游离钙离子，激光扫描共聚焦显微镜测定［Ca²⁺］_i的变化。结果 在低氧复氧、H₂O₂以及高浓度的L-谷氨酸损伤后，外源性谷氨酸（27 μmol·L^-1）均不能引起培养乳大鼠星形胶质细胞正常的［Ca²⁺］_i升高，反而使［Ca²⁺］_i分别降低(3.3±1.6)%，(81±11)%和(81±7)%；损伤前预先给予GbE（10 mg·L^-1）不能明显改善星形胶质细胞的谷氨酸反应，但预先给予GbE（100 mg·L^-1）后，27 μmol·L^-1谷氨酸可使损伤的星形胶质细胞［Ca²⁺］_i分别升高(135±98)%，(117±93)%和(89±36)%。结论低氧复氧、H₂O₂以及高浓度的L-谷氨酸均能损伤星形胶质细胞的谷氨酸反应，影响神经细胞与胶质细胞的双向交流。GbE能明显逆转不同损伤后谷氨酸诱导星形胶质细胞［Ca²⁺］_i的异常变化，使星形胶质细胞在不同损伤时能维持正常功能，该作用可能与GbE的脑保护作用有关。     

蛇床子素对豚鼠离体回肠和结肠带的作用

以豚鼠离体回肠和结肠带为标本,观察蛇床子素(Ost)的作用与Ca²⁺)的关系。结果表明:Ost和钙拮抗剂Ver产生剂量依赖性抑制乙酰胆碱(ACh)、组胺及KCl所致回肠条或结肠带的收缩;非竞争性拮抗CaCl₂累积量—效曲线,pD₂分别为4.41±0.15,7.0±0.2。Ost 100μmol/L和Ver 1μmol/L均能对抗小剂量Ca²⁺所致结肠带收缩,但被加入较大量Ca²⁺所取消。Ost和Ver均能抑制ACh诱导的依内钙性收缩,不影响依外钙性收缩。结果提示Ost具有钙拮抗作用,其作用方式与Ver类似。     

蝙蝠葛碱对异丙肾上腺素和Ca2+量效反—应及猫乳头肌电—机械活动的影响

蝙蝠葛碱对异丙肾上腺素量—效反应的影响与戊脉安和粉防己碱相似,不同于β-受体竞争性拮抗剂心得安。对Ca²⁺量—效反应的影响,亦与戊脉安和粉防己碱相似,表现为竞争性和非竞争性双重拮抗作用。在对猫乳头肌电—机械活动影响方面,对SEG的影响类似奎尼丁:R波降低,增宽,R-T延长;但同时显著抑制收缩力。结果说明蝙蝠葛碱可能具有“钙拮抗剂样”抗Ca²⁺作用和“奎尼丁样’抑制Na⁺内流的作用。     

阿托伐他汀的肝毒性机制研究

目的 研究阿托伐他汀肝毒性损伤作用及机制。方法 将24只Wistar han雄鼠分为对照组和阿托伐他汀低（68.5mg/kg）、高剂量组（205.5 mg/kg）,按照10 mL/kg的药液体积给药,溶媒对照组ig等体积5% CMC-Na,连续ig 28 d。检测血清中天门冬氨酸氨基转移酶（AST）、丙氨酸氨基转移酶（ALT）、碱性磷酸酶（ALP）、尿素氮（BUN）和血肌酐（CRE）的含量,HE染色观察肝组织病理。在体外,HepG2细胞经传代培养后,给予阿托伐他汀干预24 h,检测细胞存活率,丙二醛（MDA）水平、Na⁺-K⁺-ATP酶和Ca²⁺-Mg²⁺-ATP酶活性及线粒体膜电位。结果 与对照组比较,阿托伐他汀高剂量组大鼠肝细胞弥漫性肿胀,核分裂多见,部分肝细胞极性消失,排列紊乱（P<0.05）。与对照组比较,阿托伐他汀高剂量组给药后血清中ALT和AST显著升高（P<0.05、0.01）。在体外,与对照组比较,阿托伐他汀125、250、500 μmol/L能明显抑制细胞存活率（P<0.05、0.001）。与对照组比较,阿托伐他汀500 μmol/L HepG2细胞MDA含量明显升高（P<0.01）。与对照组比较,阿托伐他汀125 μmol/L能使Na⁺-K⁺-ATP酶活性增强,500 μmol/L使Na⁺-K⁺-ATP酶活性降低（P<0.001）。与对照组比较,阿托伐他汀125、250、500 μmol/L均能使能使Ca²⁺-Mg²⁺-ATP酶活性降低（P<0.01,0.001）。与对照组比较,阿托伐他汀125、250、500 μmol/L均能降低线粒体膜电位（P<0.001）。结论 阿托伐他汀高剂量可导致肝组织损伤,其毒性作用通过破坏细胞的线粒体膜电位,抑制Na⁺-K⁺-ATP酶、Ca²⁺-Mg²⁺-ATP酶活性,细胞膜脂质过氧化,从而破坏细胞内微环境的平衡,导致细胞凋亡和坏死。     

可乐定镇痛与中枢胆碱能系统关系的研究

本文通过小鼠光辐射热甩尾实验证明毛果芸香碱对可乐定镇痛具有增强作用,而阿托品则具有拮抗作用。阿托品对可乐定镇痛的拮抗可能不是通过竞争受体的机制,因阿托品只有达10~(-4)M/L时方可减少(~3H)-可乐定的特异性结合。给大鼠侧脑室注射密胆碱(30μg/只)明显减弱可乐定(2mg/kg,S·C)的镇痛效应。结果提示可乐定镇痛效应的充分发挥需要中枢胆碱能系统功能的完整。     

可乐定抑制胃肠运动及机理研究

可乐定(15～120μg/kg,sc)剂量依赖式地抑制小鼠及大鼠胃肠推进运动及小鼠排便反射,此作用明显强于吗啡。可乐定(120μg/kg·d×10d,sc)对小鼠上述作用未产生耐受性。icv可乐定(12μg/kg)抑制大鼠胃肠推进运动作用强于sc同剂量的可乐定。育亨宾(0.5～5mg/kg,sc)剂量依赖式地拮抗可乐定对小鼠胃肠推进运动及排便的抑制作用。     

Concurrent nimodipine attenuates the withdrawal signs and the increase of cerebral dihydropyridine binding after chronic morphine treatment in rats

Summary The effect of chronic administration of dihydropyridine calcium channel antagonist nimodipine (1 mg/kg/day) given concurrently with morphine on the signs of morphine withdrawal and on the [³H]nitren-dipine binding in the rat brain has been investigated. Chronic morphine administration in increasing daily doses from 20 mg/kg to 70 mg/kg for 24 days and consequent withdrawal for 24 h induced loss of body weight, wet dog shakes, episodes of writhing and yawning behaviour. The density of [³H]nitrendipine binding was elevated in the cortex and limbic structures but not in the striatum after chronic morphine treatment. Chronic concurrent administration of nimodipine prevented the loss of body weight and reduced the scores of wet dog shakes and writhing, but did not affect yawning behaviour at 24h after morphine withdrawal. The concurrent nimodipine treatment also prevented the rise in the density of central dihydropyridine binding sites which occurred upon chronic morphine treatment. These results suggest that chronic nimodipine treatment attenuates the development of the withdrawal signs which occur upon the termination of chronic morphine treatment by preventing the up-regulation of the central dihydropyridine-sensitive binding sites. Correspondence to: L. Ahtee at the above address     

去甲肾上腺素能系统对埃必定镇痛作用的影响

在大鼠电刺激甩尾测痛模型上,sc或icv埃必定(ipalbidine,Ipa)均具有剂量依赖性的镇痛作用,而脊髓蛛网膜下腔注射Ipa人产生镇痛作用;预先给予利血平可以取消scIpa的镇痛作用,这一作用可被icv补充NE所翻转;电解损毁大鼠叹侧蓝斑,ip二乙基二硫代氨基甲酸钠200mg·kg^-1,酚妥拉明ip10mg·kg^-1或icv150μg和sc哌唑嗪5mg·kg^-1均能使Ipa的镇痛作用明显减弱或消失,而sc育亨宾5mg·kg^-1和ip普萘洛尔10mg·kg^-1对Ipa的镇痛作用无明显影响。上述结果提示Ipa在中枢有镇痛作用,其部位主要在脊髓以上的神经结构,Ipa的镇痛作用可能与去甲肾上腺素能系统的a₁受体有关,而与a₂和β受体无明显关系。     

A study of the sensitivity of rat brain alpha2-adrenoceptors during chronic antidepressant treatments

Summary Two experimental approaches were used to study the effect of chronic antidepressant treatments on the functioning of central alpha₂-adrenoceptors. In one, the effect of antidepressant treatment on the ability of a low dose of clonidine (25 g/kg) to lower rat brain 3-methoxy-4-hydroxyphenylethyleneglycol sulphate (MHPG-SO₄) levels was studied. In the other, potential treatment-induced alterations in rat frontal cortex ³H-clonidine binding were determined. The same cortical tissue was also studied in parallel for ³H-dihydroalprenolol binding.Of the tricyclics imipramine, amitriptyline and nortriptyline, only chronic imipramine (10 mg/kg b.i.d. for 14 days) attenuated the clonidine-induced reduction in brain MHPG-SO₄ levels. Repeated electroconvulsive shock therapy (100 mA for 1 s once daily for 10 days), but not chronically administered pargyline, also antagonized the neurochemical response to clonidine.The following long-term antidepressant treatments were investigated for their effect on rat frontal cortex ³H-clonidine and ³H-dihydroalprenolol binding: desipramine, imipramine, nortriptyline, amitriptyline, mianserin, iprindole, nisoxetine, pargyline and electroconvulsive shock therapy. Only chronic pargyline (25 mg/kg once daily for 14 days) altered cortical ³H-clonidine binding. Scatchard analysis revealed that the drug-induced decrease was due to a reduction in the number of recognition sites with no change in affinity. With the exceptions of mianserin and nisoxetine, all other seven forms of antidepressant treatment decreased cortical ³H-dihydroprenolol binding, Scatchard analysis revealing a diminution in the number of recognition sites.The results of this, and previous studies, indicate that under the dosage regimens employed only some forms of long-term antidepressant treatments induce a down-regulation in the functioning of rat brain presynaptic alpha₂-adrenoceptors, as assessed by the clonidine-MHPG-SO₄ model. No correlation was found between treatment-induced alterations in the characteristics of cortical ³H-clonidine recognition sites and the effect of identical treatment on the clonidine-induced reduction in rat brain MHPG-SO₄ levels.To unequivocally assume that drug-induced changes in central ³H-clonidine recognition sites reflect alterations in the functioning of central presynaptic alpha₂-adrenoceptors may be open to question.     

中枢与外周α-肾上腺素能受体激动效应不一致性的原理分析

对戊巴比妥钠麻醉家兔,静脉注射α-肾上腺素能受体拮抗剂育亨宾(Yohimbine)或γ-氨基丁酸(GABA)受体拮抗剂苦味毒(picrotoxin)均可明显对抗侧脑室注射氯压定(clonidine)的降血压作用。但是育亨宾不能阻断侧脑室注射GABA的中枢降压作用,而苦味毒则能完全阻断其降压效应。家兔经GABA合成抑制剂氨基脲(Semicarbazide)静脉注射予处理后,动物于给药后3～4小时出现强烈惊厥,说明脑内GABA已降低到一定水平。此时用局部麻醉剂及肌松剂处理,在人工呼吸情况下,氯压定静脉注射的降压作用比不给氨基脲予处理的对照组动物显著减弱。以上结果启示,中枢肾上腺素能受体激动而产生的降压作用有可能是通过GABA能抑制性神经元而实现。     

Characterization of two distinct alpha-adrenoceptor binding sites in smooth muscle cell membranes from rat and bovine aorta

Summary In order to characterize postjunctional alpha adrenoceptor binding sites of aortic smooth muscle, the specific binding of (³H)prazosin and (³H)yohimbine to membranes prepared from the medial layers of rat and bovine thoracic aorta was investigated. Binding of (¹²⁵I)-BE 2254 (2-[B-(4-hydroxyphenyl)-ethylaminomethyl] tetralone) and (³H)RX 781094 (idazoxan) was also examined in bovine membranes. Each of the ligands displayed saturable, specific binding to a single population of sites; the K _D values of the respective ligands were similar in the two animal species. The number of (³H)prazison and (¹²⁵I)BE 2254 binding sites (160–190 fmol · mg protein^–1 in the two species) was higher than the number of (³H)yohimbine and (³H)RX 781094 binding sites (110–120 fmol · mg protein^–1 in the bovine and 50 fmol · mg protein^–1 in the rat). Alpha-adrenoceptor ligands inhibited binding of the ligands with the following orders of potency: prazosin > BE 2254 > yohimbine > RX 781094 > clonidine in the case of (³H)-prazosin, and yohimbine > RX 781094 > clonidine > prazosin in the case of (³H)yohimbine. Methoxamine, in concentrations up to 10 M, was without effect on the binding of either ligand. The absence or presence of Na⁺, K⁺ or Ca²⁺ added at physiological concentrations did not change the order of potency of displacing ligands whereas Ca²⁺ reduced by 50% the numbers of (³H)prazosin and (³H)-yohimbine sites and Na⁺ increased by 3-fold the affinity of (³H)yohimbine.It is concluded that post-junctional membranes from rat and bovine aortic smooth muscle contain two distinct ₁- and ₂-adrenoceptor binding sites, the number of the latter being less than the number of the former.     

Characterization of non-adrenergic [3H]clonidine binding sites in rat stomach: high affinity of imidazolines,guanidines and sigma ligands

We have identified and characterized non-adrenergic [³H]clonidine binding sites in rat stomach. The binding of [³H]clonidine was rapid, reversible, partly specific (as defined by cirazoline 0.1 mmol/l; 68% specific binding at [³H]clonidine 10 nmol/l), saturable and of high affinity. The specific binding of [³H]clonidine to rat stomach membranes was concentration-dependently inhibited by various imidazolines and guanidines including the sigma site ligand 1,2-di-(2-tolyl)guanidine (DTG), by the butyrophenone derivative haloperidol and by the piperidine derivative (+)-3-PPP[(R)-3-(3-hydroxyphenyl)-N-propylpiperidine]; the latter two compounds are also known to exhibit affinity for sigma sites. In contrast, rauwolscine, histamine, ranitidine and the non-hydrolysable GTP-analogue Gpp(NH)p (5 guanylylimidodiphosphate) did not, or with negligible affinity, inhibit [³H]clonidine binding. In most cases, the competition curves were best fitted to a two-site model. The rank order of affinity for the high affinity site (in a few cases for a single detectable site) was as follows: cirazoline>idazoxanDTG>(+)-3-PPP> clonidine>guanabenz>haloperidol. This rank order is not compatible with the pharmacological properties of either I₁- or I₂-imidazoline binding sites. However, the ability of haloperidol, (+)-3-PPP and DTG to displace [³H]clonidine (the latter two with high affinity) suggests that the [³H] clonidine binding sites in rat stomach may be related to sigma-like sites.