长春西汀对大鼠心肌细胞钠电流的抑制作用

目的：研究长春西汀对心肌细胞钠电流的作用。方法：用全细胞膜片箝技术记录大鼠心肌细胞钠电流。结果：长春西汀可逆性抑制心肌细胞钠电流的作用为剂量依赖性和电压依赖性，但未发现频率或使用依赖性。长春西汀１０－８０μｍｏｌ·Ｌ＾－１，对钠电流的抑制作用为１３％±２％至７５％±６％，半数抑制浓度ＩＣ５０值（９５％可信限）为３６．４（２８．１－４７．１）μｍｏｌ·Ｌ＾－１，在膜电位以１０ｍＶ的间隔从－９０ｍＶ阶     

Efectsofmoxonidineinjectedintorostralventrolateralmedulaonbloodpressure,heartrate,andrenalsympatheticnerveactivityinrats

目的：观察延髓腹外侧头端（ＲＶＬＭ）注射莫索尼定（Ｍｏｘ）对麻醉大鼠血压（ＢＰ）、心率（ＨＲ）及肾交感神经放电（ＲＳＮＡ）的影响．方法：麻醉大鼠ＲＶＬＭ注射１μＬＭｏｘ１，１０，１００μｍｏｌ·Ｌ－１，同步记录ＢＰ，ＨＲ及ＲＳＮＡ．结果：Ｍｏｘ１，１０，１００μｍｏｌ·Ｌ－１分别使ＢＰ从１３９±１０ｋＰａ降至１３０±１７ｋＰａ（Ｐ＜００５），１３８±１８ｋＰａ至１１４±１５ｋＰａ（Ｐ＜００１），ａｎｄ１３９±１９ｋＰａ至９４±１７ｋＰａ（Ｐ＜００１）．Ｍｏｘ不影响ＨＲ．Ｍｏｘ１μｍｏｌ·Ｌ－１增加ＲＳＮＡ５０％（Ｐ＜００５），１０μｍｏｌ·Ｌ－１对ＲＳＮＡ无影响（Ｐ＞００５），１００μｍｏｌ·Ｌ－１则降低ＲＳＮＡ２３％（Ｐ＜００５）．在缓冲神经切断大鼠，Ｍｏｘ１０μｍｏｌ·Ｌ－１抑制ＲＳＮＡ５０％（Ｐ＜００５），明显不同于缓冲神经完整的动物（Ｐ＜００１）．结论：麻醉大鼠ＲＶＬＭ注射Ｍｏｘ可降低ＢＰ，但不影响ＨＲ，且ＲＳＮＡ变化与其降压作用并不平行     

Effects of berberine on L-and T-type calcium channels in guinea pig ventricular myocytes

目的：研究小檗碱（Ｂｅｒ）对心室肌细胞钙通道的影响．方法：全细胞膜片箝技术．结果：Ｂｅｒ（１０，３０μｍｏｌ·Ｌ－１）使豚鼠心室肌细胞Ｌ型钙流由１４００±２４７ｐＡ分别减至９７８±２０４ｐＡ及６１７±２３ｐＡ（ｎ＝５，Ｐ＜００５），抑制效应呈浓度依赖及非频率依赖，其电流－电压曲线的峰值下降．Ｂｅｒ（１０μｍｏｌ·Ｌ－１）使Ｌ型钙流失活曲线的最大半激活电压由－２７８ｍＶ变为－３４２ｍＶ，斜率因子由９２２变为１３０３，对激活曲线无影响．Ｂｅｒ（１０，３０μｍｏｌ·Ｌ－１）使Ｔ型钙流峰值由加药前的１５４±８０ｐＡ降至１０１±７８ｐＡ及４８±４５ｐＡ（ｎ＝８，Ｐ＜００５）．结论：Ｂｅｒ对Ｌ和Ｔ型钙通道均有抑制作用．     

Effects of norepinephrine and isopentenyladenosine on Na~ /Ca~(2 ) exchangecurrents in isolated guinea pig ventricular myocytes

目的：研究去甲肾上腺素（ＮＥ）和异丙肾上腺素（Ｉｓｏ）对Ｎａ＋／Ｃａ２＋交换电流的影响及受体调控机制．方法：应用全细胞电压钳技术的斜坡脉冲程序，测定离体豚鼠心肌细胞准稳态电流电压关系曲线．结果：ＮＥ０００５，００５和５μｍｏｌ·Ｌ－１分别使膜电位＋５０ｍＶ时的Ｎｉ２＋敏感电流增加２９％±９％，７２％±１１％和１２０％±３１％；Ｉｓｏ１５，１５０和１５００ｎｍｏｌ·Ｌ－１分别使该电流增加２８％±２８％，５６％±１３％和１０２％±１２％．ＮＥ和Ｉｓｏ的这种增强效应能被普萘洛尔１０μｍｏｌ·Ｌ－１完全阻断，而酚妥拉明５０μｍｏｌ·Ｌ－１无此作用．结论：ＮＥ和Ｉｓｏ通过兴奋心脏β肾上腺素受体使Ｎａ＋／Ｃａ２＋交换电流增加．     

Mechanisms of artemisinin antiarrhythmic action

采用全细胞电压钳技术,以确定青蒿素对分离的豚鼠心室肌细胞和狗的浦肯野纤维钾离子电流的影响．在豚鼠心室肌细胞,青蒿素呈浓度依赖关系显著降低内向整流钾电流〔ＩＫ１,膜电位为－１００ｍＶ时,ＩＣ５０为（７．２±０．８）μｍｏｌ·Ｌ－１〕,且这种抑制作用不呈现频率依赖性．５０μｍｏｌ·Ｌ－１的青蒿素降低延迟整流钾电流（ＩＫ）：时间依赖性外向钾电流（ＩＫｓｔｅｐ）在膜电位为＋４０ｍＶ时减少（３８±１０）％．尾电流步阶分析提示,ＩＫ的快组分（ＩＫｒ）和慢组分（ＩＫｓ）均被抑制．在犬浦肯野纤维,青蒿素明显抑制瞬时外向钾电流（Ｉｔｏ）,ＩＣ５０为（４．２±０．３）μｍｏｌ·Ｌ－１．实验结果表明,青蒿素以相似效率抑制ＩＫ１,Ｉｔｏ和ＩＫ,其抗心律失常作用可能与抑制ＩＫ１,Ｉｔｏ,ＩＫｒ和ＩＫｓ有关．     

l-S·R-daurisoline protects cultured hippocampal neurons against glutamate neurotoxicity by reducing nitric oxide production

目的：探讨ｌＳ·Ｒ蝙蝠葛苏林碱（ＤＳ）保护神经元的作用机制．方法：原代培养大鼠海马神经细胞,用台盼蓝染色和ＭＴＴ法检测神经细胞损伤,以去内皮的大鼠胸主动脉作为分析ＮＯ含量的生物检测器．结果：ＤＳ００１－１０μｍｏｌ·Ｌ－１剂量依赖性地抑制谷氨酸（Ｇｌｕ）神经毒性,ＩＣ５０为２８μｍｏｌ·Ｌ－１（９５％可信限为１２－５９μｍｏｌ·Ｌ－１）,ＤＳ１０μｍｏｌ·Ｌ－１能够抑制Ｇｌｕ引起的主动脉条舒张,但对亚硝基铁氰化钠（ＳＮＰ）的动脉条舒张和神经毒性无明显的影响．表明ＤＳ不能直接对抗ＮＯ的毒性,但能抑制Ｇｌｕ刺激ＮＯ的产生．结论：ＤＳ对抗Ｇｌｕ引起的神经毒性的作用与抑制Ｇｌｕ刺激ＮＯ的合成有关．     

NAD-and NADP-dependent 11β-hydroxysteroid dehydrogenase isoforms in guinea pig kidney with gossypol inhibition

探讨棉酚诱发低钾血症机制．方法：从豚鼠肾脏皮质制备１１βＯＨＳＤ，反相高效液相测定该酶活性．结果：依赖辅酶Ｉ的１１βＯＨＳＤ的Ｖｍａｘ＝０６４ｍｍｏｌ·ｈ－１／ｇｐｒｏｔｅｉｎ，Ｋｍ＝００７μｍｏｌ；依赖辅酶ＩＩ的１１βＯＨＳＤ的Ｖｍａｘ＝１７５ｍｍｏｌ·ｈ－１／ｇｐｒｏｔｅｉｎ，Ｋｍ＝０２１μｍｏｌ．棉酚对它们的抑制有显著差异，ＩＣ５０（９５％可信限）前者为５０２（４８３－５２０）μｍｏｌ，后者为１１４３（１０９８－１１８８）μｍｏｌ，抑制常数Ｋｉ分别为９６ｍｍｏｌ·Ｌ－１和３４０ｍｍｏｌ·Ｌ－１．结论：抑制依赖辅酶Ｉ的１１βＯＨＳＤ是棉酚诱发低钾血症的更主要的生理因素．     

Effects of N-methyl berbamine on delayed outward potassium current in isolated rat hepatocytes

目的：研究Ｎ甲基小檗胺（ＮＭＢ）对大鼠肝细胞外向钾电流的影响．方法：应用膜片箝技术和全细胞记录方法，箝制电位－５０ｍＶ，指令电位＋３０至＋１４０ｍＶ，持续时间９００ｍｓ．结果：ＮＭＢ以浓度依赖方式降低外向钾电流．电流幅值在２０，５０，４００ｎｍｏｌ·Ｌ－１和５０μｍｏｌ·Ｌ－１时分别从４４±１０（ｎ＝４），２５±１８（ｎ＝４），５８±２１（ｎ＝５），４６±１３（ｎ＝６）ｎＡ降到３６±０４（Ｐ＞００５），２１±１６（Ｐ＞００５），３７±１６（Ｐ＜００５），２３±１３（Ｐ＜００１）ｎＡ．抑制率分别为１０％，１５％，３７％，５１％．结论：ＮＭＢ是一种钾通道阻断剂．     

Bradykinin B_2receptor antagonist icatibant reduces inhibitory effect of captopril on growth of cultured neonatal rat cardiomyocytes

目的：观察内源性激肽对培养新生大鼠心肌细胞生长的影响及其机制．方法：［３Ｈ］尿嘧啶和［３Ｈ］亮氨酸参入法检测ＲＮＡ和蛋白质合成速率，Ｎｏｒｔｈｅｒｎ杂交检测ｃｍｙｃ和ｃｆｏｓｍＲＮＡ表达．结果：卡托普利１００μｍｏｌ·Ｌ－１孵育４８ｈ显著抑制［３Ｈ］尿嘧啶和［３Ｈ］亮氨酸参入，孵育２ｈ明显抑制ｃｍｙｃ和ｃｆｏｓ基因表达．ＡｎｇⅡ１μｍｏｌ·Ｌ－１处理４８ｈ刺激ＲＮＡ和蛋白质合成，１ｈ可上调ｃｍｙｃ和ｃｆｏｓ表达．Ｃａｐ１００μｍｏｌ·Ｌ－１部分抑制ＡｎｇⅡ上述作用．缓激肽Ｂ２受体拮抗剂Ｉｃａ（０１－１０μｍｏｌ·Ｌ－１）剂量依赖性阻断Ｃａｐ作用．结论：内源性激肽经ＢＫＢ２受体介导对心肌细胞的生长起负调节作用     

Blocking effects of phentolamine on L-type calcium current and ATP-sensitive potassium current in guinea pig ventricular myocytes

目的：研究酚妥拉明对豚鼠心室肌细胞Ｌ型钙电流及ＡＴＰ敏感钾电流的作用．方法：用膜片钳的全细胞记录方式观察钙电流和ＡＴＰ敏感钾电流．结果：酚妥拉明５，２５和１００μｍｏｌ·Ｌ－１对钙电流呈浓度依赖性和非电压依赖性的抑制作用，抑制率分别为１７％，２３％和３０％，而对电流电压关系没有影响．这一抑制作用与酚妥拉明对α１和α２受体的作用无关．酚妥拉明１００μｍｏｌ·Ｌ－１可显著抑制ＤＮＰ诱导产生的ＡＴＰ敏感钾电流，抑制率为７５％．结论：酚妥拉明显著抑制豚鼠心室肌细胞Ｌ型钙电流和ＡＴＰ敏感钾电流．     

Efficacy of gut lavage,hemodialysis, and hemoperfusion in the therapy of paraquat or diquat intoxication

Clinical and in vitro investigations were carried out to test the efficacy of gut lavage, hemodialysis, and hemoperfusion in the treatment of poisoning with paraquat or diquat. In a patient suffering from diquat intoxication 130 times more diquat was removed by gut lavage 30 h after ingestion than was removed by complete aspiration of the gastric contents.Determination of in vitro clearances for paraquat and diquat by hemodialysis showed that, at serum concentrations of 1–2 ppm, such as are frequently encountered in poisoning in man, toxicologically relevant quantities of herbicide cannot be removed from the body. At a concentration of 20 ppm, on the other hand, hemodialysis proved to be effective, the clearance being 70 ml/min at a blood flow rate of 100 ml/min. The efficacy of hemoperfusion with coated activated charcoal was on the whole better. Especially at concentrations around 1–2 ppm, the clearance values for hemoperfusion were some 5–7 times higher than those for hemodialysis.In a patient suffering from paraquat poisoning, both hemodialysis as well as hemoperfusion were carried out. The in vitro results could be confirmed: At serum concentrations of paraquat less than 1 ppm no clearance could be obtained by hemodialysis while by hemoperfusion with activated charcoal quite high clearance values were measured and the serum level dropped down to zero.

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Zusammenfassung Klinische Untersuchungen und Laboratoriumsversuche wurden durchgeführt, um die Wirksamkeit von Darmspülung, Hämodialyse und Hämoperfusion bei Paraquat- und Deiquat-Vergiftungen zu prüfen.Bei einem Patienten wurde 30 Std nach Deiquat-Aufnahme durch Darmspülung 130mal mehr Deiquat entfernt als durch vollständige Aspiration des Mageninhaltes. In vitro-Versuche ergaben, daß bei Blutserumkonzentrationen von 1–2 ppm, die bei Vergiftungen oft gemessen werden, durch Hämodialyse keine toxikologisch relevanten Paraquat- oder Deiquat-Mengen entfernt werden können. Dagegen erwies sich die Hämodialyse bei 20 ppm und einer Blutumlaufgeschwindigkeit von 100 ml/min mit einer Clearance von 70 ml/min als wirksam. Die Hämoperfusion mit beschicheter Aktivkohle war in diesen Versuchen aber eindeutig überlegen, denn insbesondere bei Konzentrationen um 1–2 ppm waren die Clearance-Werte 5–7mal höher als bei der Hämodialyse.Die in vitro-Ergebnisse wurden bei einem Patienten mit einer Paraquat-Vergiftung bestätigt: Bei Konzentrationen unter 1 ppm war die Hämodialyse wirkungslos, während durch Hämoperfusion relativ hohe Clearance-Werte erreicht wurden, so daß der Serumspiegel rasch unter die Nachweisgrenze abfiel.

     

In vitro studies on sterically stabilized liposomes (SL) as enzyme carriers in organophosphorus (OP) antagonism

This study describes a new approach for organophosphorous (OP) antidotal treatment by encapsulating an OP hydrolyzing enzyme, OPA anhydrolase (OPAA), within sterically stabilized liposomes. The recombinant OPAA enzyme was derived from Alteromonas strain JD6. It has broad substrate specificity to a wide range of OP compounds: DFP and the nerve agents, soman and sarin. Liposomes encapsulating OPAA (SL)* were made by mechanical dispersion method. Hydrolysis of DFP by (SL)* was measured by following an increase of fluoride ion concentration using a fluoride ion selective electrode. OPAA entrapped in the carrier liposomes rapidly hydrolyze DFP, with the rate of DFP hydrolysis directly proportional to the amount of (SL)* added to the solution. Liposomal carriers containing no enzyme did not hydrolyze DFP. The reaction was linear and the rate of hydrolysis was first order in the substrate. This enzyme carrier system serves as a biodegradable protective environment for the recombinant OP-metabolizing enzyme, OPAA, resulting in prolongation of enzymatic concentration in the body. These studies suggest that the protection of OP intoxication can be strikingly enhanced by adding OPAA encapsulated within (SL)* to pralidoxime and atropine.     

Aquatic Insects and Trace Metals: Bioavailability,Bioaccumulation, and Toxicity

Abstract

The uptake of metals from food and water sources by insects is thought to be additive. For a given metal, the proportions taken up from water and food will depend both on the bioavailable concentration of the metal associated with each source and the mechanism and rate by which the metal enters the insect. Attempts to correlate insect trace metal concentrations with the trophic level of insects should be made with a knowledge of the feeding relationships of the individual taxa concerned. Pathways for the uptake of essential metals, such as copper and zinc, exist at the cellular level, and other nonessential metals, such as cadmium, also appear to enter via these routes. Within cells, trace metals can be bound to proteins or stored in granules. The internal distribution of metals among body tissues is very heterogeneous, and distribution patterns tend to be both metal and taxon specific. Trace metals associated with insects can be both bound on the surface of their chitinous exoskeleton and incorporated into body tissues. The quantities of trace meals accumulated by an individual reflect the net balance between the rate of metal influx from both dissolved and particulate sources and the rate of metal efflux from the organism. The toxicity of metals has been demonstrated at all levels of biological organization: cell, tissue, individual, population, and community. Much of the literature pertaining to the toxic effects of metals on aquatic insects is based on laboratory observations and, as such, it is difficult to extrapolate the data to insects in nature. The few experimental studies in nature suggest that trace metal contaminants can affect both the distribution and the abundance of aquatic insects. Insects have a largely unexploited potential as biomonitors of metal contamination in nature. A better understanding of the physico-chemical and biological mechanisms mediating trace metal bioavailability and exchange will facilitate the development of general predictive models relating trace metal concentrations in insects to those in their environment. Such models will facilitate the use of insects as contaminant biomonitors.     

Alzheimer’s disease – current trends in basic and clinical research. Highlights from the 16th ECNP

Advances in the molecular biological knowledge of neuronal nicotinic acetylcholine receptors (nAChRs) have led to a growing interest by the pharmaceutical industry in the development of novel compounds that selectively modulate nAChR function. The ability of (-)-nicotine, an activator of nAChRs, to enhance attentional aspects of cognition in animals and humans, to exert neuroprotective and anxiolytic-like effects, and presumably to mediate the negative correlation between smoking and Alzheimer's (and Parkinson's) Disease, has focused interest on the potential therapeutic utility of modulators of nAChR function for treatment of some of the deficits associated with these progressive, neurodegenerative conditions. Numerous compounds are known which activate nAChRs and which might serve as lead compounds toward the development of such agents. The pharmacologic diversity of neuronal nAChR subtypes suggests the possibility of developing selective compounds which would have more favourable side-effect profiles than existing agents. This broader class of agents, collectively called cholinergic channel modulators (ChCMs), is anticipated to encompass compounds which would have more favourable side-effect profiles than existing agents, which generally exhibit low selectivity. This selectivity may be achieved by preferentially activating some subtypes of nAChRs (i.e., Cholinergic Channel Activators, ChCAs) or inhibiting the function of other subtypes (Cholinergic Channel Inhibitors, ChCIs). An overview of the biology of nAChRs and the rationale for the use of ChCMs for the treatment of dementia related to neurodegenerative diseases are presented, followed by a discussion of lead compounds and compounds under consideration for clinical evaluation.     

Steroidal sapogenin contents in some domestic plants

In order to find out the values of the steroid resources for the future use. the compositions and contents of steroidal sapogenins from 13 domestic plants have been investigated. As a result,Dioscorea nipponica, D. quinqueloba andSmilax china were found to have large amount of diosgenin. And pennogenin inTrillium kamtschaticum andParis verticillata, yuccagenin inAllium fistulosum, hecogenin inAgave americana and neochlorogenin inSolanum nigum were appeared to be major steroidal sapogenins.