心肌梗死后心室肌细胞钙通道改变的实验研究

目的 探讨L型钙通道在急性心肌梗死(AMI)后室性心律失常发生的作用及机制.方法开胸冠脉结扎制备兔AMI模型,于1周和2个月处死动物分离心室肌细胞,以膜片钳技术记录梗死及周边区心外膜细胞L型钙通道电流(Ⅰca-L)的变化.结果AMI兔梗死周边区心外膜细胞Ⅰca-L受到抑制,Ⅰ-Ⅴ曲线上移,其峰值电流密度在正常对照组、梗死后1周和2个月分别为(-5.58±1.53)pA/pF、(-3.52±0.93)pA/pF(n=6,与对照组比较P＜0.05)和(-4.84±1.48)pA/pF(n=11,与对照组比较P＜0.05),但Ⅰ-Ⅴ曲线的形态轨迹不变.其失活曲线左移,失活速度加快,半数最大失活电位分别为(-13.1±4.2)mV、(-25.9±7.0)mV和(-21.3±5.6)mV,P＜0.05. 结论AMI后梗死周边带心外膜细胞Ⅰca-L通道受抑制,可能为AMI后发生室性心律失常的机制之一;梗死后2个月钙通道异常程度减轻,有恢复正常的趋势.     

环维黄杨星D延长大鼠心室肌细胞APD作用的分子机制研究

目的　研究环维黄杨星D对分离的大鼠心室肌细胞内向整流钾电流 (IK1 )、瞬时外向钾电流 (Ito)、L 型钙电流(ICa L)和动作电位时程 (APD)的影响。方法　采用全细胞膜片钳技术记录大鼠心室肌细胞IK1 、Ito、ICa L 和APD。结果　 1和10 μmol·L- 1 环维黄杨星D明显延长分离大鼠心室肌细胞APD50 和APD90 ,10 μmol·L- 1 可明显降低静息膜电位 (RP)。环维黄杨星D对IK1 内向电流和外向电流均有明显抑制作用 ,当指令电压为 - 10 0mV时 ,1和 10 μmol·L- 1 环维黄杨星D分别使IK1 电流密度从给药前的 ( - 8.0± 1.1)pA pF降至 ( - 4 .1± 0 .7)pA pF和 ( - 3.4± 0 .8)pA pF ;当指令电压 - 30mV时 ,分别使IK1 电流密度从 ( 1.10± 0 .2 4 )pA pF降至 ( 0 .6 1± 0 .18)pA pF和 ( 0 .36± 0 .11)pA pF ;在钳制电位从 0到 + 6 0mV之间 ,环维黄杨星D明显抑制Ito,当指令电压 4 0mV时 ,1和 10 μmol·L- 1 环维黄杨星D分别使Ito电流密度从给药前的 ( 8.9± 2 .0 )pA pF降至 ( 5 .5± 1.2 )pA pF和 ( 4 .9± 0 .9)pA pF。环维黄杨星D浓度依赖性抑制ICa L,在指令电压为 10mV时 ,1和 10 μmol·L- 1 分别使ICa L电流密度从给药前的 ( - 9.9± 1.8)pA pF降至 ( - 6 .4± 1.4 )pA pF和 ( - 4 .2± 0 .6 )pA pF。结论　环     

硫酸镁对兔跨室壁L型钙电流不均一性的影响

目的　研究硫酸镁对兔左室游离壁心内膜下心肌(Endo) ,中层心肌 (M )和心外膜下心肌 (Epi)L型钙电流(ICa,L)的影响 ,探讨硫酸镁治疗尖端扭转性室型心动过速(Tdp)时 ,减少跨室壁复极离散 (TDR)离子流基础。 方法　全细胞膜片钳技术分别记录兔心室三层心肌细胞的ICa,L。结果　细胞外液加入 1mmol·L-1硫酸镁时 ,兔Endo ,M和Epi的ICa ,L密度分别为 :(9 6± 1 1) pA/pF、(10 3± 0 9)pA/pF、(7 1± 0 7) pA/pF ,加入 2mmol·L-1硫酸镁时ICa ,L密度分别为 :(7 4± 0 6 ) pA/pF、(7 8± 0 5 )pA/pF、(6 7±0 8) pA/pF ;加入 3mmol·L-1硫酸镁时ICa ,L密度分别为(6 1± 0 4 ) pA/pF、(6 3± 0 5 ) pA/pF、(5 6± 0 4 ) pA/pF ,硫酸镁呈浓度依赖性地抑制心肌细胞的ICa ,L,并使跨室壁ICa ,L的不均一性减少。高浓度的硫酸镁使三层心肌细胞ICa,L的电流 电压曲线上移 ,对ICa ,L的动力学参数无明显影响。结论　硫酸镁呈浓度依赖性的减少跨室壁ICa ,L的不均一性。     

药物相关性尖端扭转型室性心动过速性别差异的离子通道研究

目的　探讨药物相关性尖端扭转型室性心动过速 (TdP)发生率性别差异的离子流基础。方法　♀、♂兔各 2 0只 ,酶解法分得左室心尖部单个细胞 ,应用全细胞膜片钳技术记录APD、Ito、IK、IK1和ICa ,L。结果　♀、♂兔心肌细胞膜电容差异无显著性 (P >0 0 5 )。♀兔APD90 (5 6 0 4± 2 6 5ms,n =15 )比♂兔APD90 (489 0± 2 0 7)ms ,n =14长 (P <0 0 5 )。IK ,tail、Ito、IK1和ICa,L在♀兔分别为 (0 71± 0 0 5 )pA/ pF、n =17,(8 2 8± 1 0 3) pA/pF、n =18,(2 4 5± 3 6 ) pA/ pF、n =12 ,(9 0± 2 3)pA/ pF、n =15 ,在♂兔分别为 (0 84± 0 0 7) pA/pF、n =18,(8 6 0± 1 2 0 ) pA/pF、n =18,(2 5 9± 4 5 ) pA/pF、n =14 ,(9 3± 2 6 )pA/ pF、n =16。♀兔IK ,tail明显低于♂兔 (P <0 0 5 ) ,而Ito、IK1和ICa,L在♀、♂兔差异无显著性 (P >0 0 5 )。结论　♀兔IK ,tail较低可能是♀兔APD90 较♂兔长及更易发生药物相关性TdP的原因。     

急性坏死性胰腺炎对心室肌细胞及L-钙通道电流的影响

目的　观察急性坏死性胰腺炎 (ANP)后心室肌细胞病理损伤及L 钙通道电流 (ICa L)的变化 ,以探讨ANP后发生心力衰竭及心律失常的机制。方法　采用牛磺胆酸钠逆行胰胆管注射建立鼠的ANP动物模型 ,1小时后处死 ,行HE、Mas son染色 ,光镜观察心肌的病理变化。应用膜片钳全细胞记录方法 ,观察ANP后 1小时心肌细胞ICa L的变化。结果　光镜下心肌纤维呈局灶性嗜酸变性及坏死 ;ANP组ICa L电流密度峰值 ( +10mV)为 ( 3 63± 0 65 )pA/pF(n =16) ,显著低于对照组( 5 46± 1 0 3 )pA/pF(n =12 ) (P <0 0 1)。结论　ANP可导致心室肌纤维发生变性和坏死 ,并可致心室肌细胞ICa L下降 ,引起心肌细胞动作电位时程缩短 ,这可能是导致ANP后出现心功能不全和心律失常的原因。     

陈旧性心肌梗死时兔心室肌细胞瞬间外向钾电流的变化

目的　观察陈旧性心肌梗死时心室肌细胞瞬间外向钾电流 (Ito)的变化 ,探讨心律失常发生的离子机制。方法　采用结扎兔冠状动脉左前降支的方法建立急性心肌梗死动物模型 ,2个月后处死动物并分离心室肌细胞 ,应用膜片钳全细胞记录方法 ,观察心肌梗死后 2个月心外膜梗死区 (MI)、远离梗死区 (REM )与正常对照组 (CON)心室肌细胞Ito的变化。结果　①心肌梗死后 2个月REM组心肌细胞电容为 ( 15 5 .7± 5 .8)pF ,明显大于CON组的 ( 12 0 .3± 6.2 ) pF和MI组的( 13 0 .4± 7.8) pF(P <0 0 5 ) ,MI组与CON组相比无统计学差异 (P >0 0 5 )。②Ito电流密度 ( +60mV时 )的对比显示 ,CON组为 ( 17.4± 5 .2 ) pA pF (n =16) ,MI组为 ( 10 6± 4 1) pA pF (n =18) ,明显低于CON组 (P <0 0 1) ;REM组为 ( 13 .2± 4 1)pA pF(n =2 3 ) ,明显低于CON组 (P <0 0 1) ,但明显高于MI组 (P <0 0 5 )。 结论　心肌梗死后心室肌细胞Ito电流密度的变化 ,可能是导致折返性室性心律失常的离子基础     

氟哌啶醇季铵盐衍生物对大鼠心室肌细胞L型钙电流的影响

目的　研究氟哌啶醇季铵盐衍生物 (F2 )对大鼠心室肌细胞L型钙电流 (ICa)的影响。方法　采用酶急性分离的单个大鼠心室肌细胞 ,应用膜片钳全细胞记录技术 ,观察F2对ICa的影响。结果　F2 (1μmol·L-1)能抑制任何一膜电压下的ICa,使峰电流从 (1775 2± 36 0 4 ) pA减少至 (46 4±12 9 1) pA (n =8,P <0 0 1) ,并使ICa的电流 -电压曲线上移 ,但不改变ICa的电压依赖特征。结论　F2 对心肌细胞膜L型钙通道具有阻断作用     

白藜芦醇对豚鼠心室肌细胞L型钙通道的影响

目的研究白藜芦醇(resveratrol,RES)对豚鼠心室肌细胞L型钙通道的影响。方法酶解法分离单个豚鼠心室肌细胞,采用全细胞膜片钳技术记录白藜芦醇对豚鼠单个心室细胞L型钙通道电流(ICa-L)的影响。结果不同浓度的RES明显抑制ICa-L,1、10、100μmol.L-1L的RES使其峰电流密度从(12.96±1.48)pA/pF减少到(11.36±1.59)、(9.96±1.51)和(7.77±0.68)pA/pF(n=6,P<0.01),冲洗后可恢复至(11.85±0.83)pA/pF。RES可使ICa-L的I-U关系曲线上移,其形状和峰值电压保持不变;RES还可使通道的激活曲线右移,但失活曲线和失活恢复时间无改变。结论白藜芦醇通过延长L型钙通道激活过程而明显抑制ICa-L,减少细胞外的钙离子内流,延长有效不应期,从而发挥抗心律失常作用。     

5—羟色胺增强去甲肾上腺素诱导的肥厚心肌L—型钙电流

目的:研究5-羟色胺(5-HT)对去甲肾上腺素(NE)诱导的大鼠肥厚心肌L-型钙电流(I_(Ca))的影响.方法:大鼠腹腔注射NE建立心肌肥厚模型;酶解分离单个心室肌细胞;全细胞膜片箝记录I_(Ca).结果:(1)腹腔注射NE第15天,大鼠左心室与体重比增加31.8％(2)肥厚心肌细胞I_(Ca)与正常心肌细胞相比,明显增加0mV时分别为4.5pA/pF±0.5pA/pF和3.5pA/pF±0.3pA/pF(P<0.01).(3)5-HT可显著增加肥厚和正常心肌细胞I_(Ca),并使最大激活电流从0mV降低至-10mV;此外,5-HT增加I_(Ca)作用在肥厚心肌细胞更为显著.(4)稳态激活和失活实验发现,5-HT对稳态激活曲线无显著影响,而影响稳态失活曲线,使半失活电压从-39.5mV±1.8mV升高至-27.8mV±1.7mV(P<0.05),而不改变钙通道电压依赖性(斜率因子k无显著变化).结论:5-HT通过改变L-型钙通道稳态失活特征而显著增加I_(Ca),此作用在肥厚心肌细胞更显著,提示在肥厚心肌5-HT更易于诱导心律失常发生.     

氯沙坦对大鼠肥厚心肌L-型钙电流的作用(英文)

目的 研究腹主动脉结扎诱发大鼠肥厚心肌L-型钙电流的变化以及用氯沙坦治疗对此变化的影响。方法　用结扎腹主动脉的方法诱发大鼠心肌肥厚模型。用全细胞膜片钳技术记录肥厚左心室肌细胞L-型钙电流。结果 肥厚组心肌细胞膜电容 (148±29 pF) 明显大于假手术组 (102±14 pF, P<0.01) 和氯沙坦治疗组 (118±27, P<0.01)。肥厚组ICa,L 峰值及电流密度均大于假手术组 (－835±124 pA vs －1404±417 pA 和(7.5±1.8 pA·pF-1 vs －0.5±2.2 pA·pF-1, P<0.01)。氯沙坦治疗组ICa,L 峰值 (－956±170 pF) 及电流密度 (－8.2±1.6 pA·pF-1) 均比肥厚组明显减小 (P<0.05)。肥厚组半数激活电压 (－20.6±1.0 mV)与假手术组 (－15.6±1.6 mV) 及氯沙坦治疗组 (－17.4±1.0 mV) 相比向负向移动 (P<0.01)。肥厚组激活曲线斜率 (5.7±0.4)比假手术组 (6.4±0.5) 略减小 (P<0.05)。肥厚组半数失活电压 (－27.6±1.9 mV) 比假手术组 (－31.4±2.2 mV) 略正移 (P<0.05)。三组心肌失活曲线斜率无差异。结论　氯沙坦 (30 mg·kg-1·d-1, ig) 可防止腹主动脉结扎诱发大鼠心肌细胞肥大的发生及相关的L-型钙电流的变化。     

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.     

Pharmacological treatment of COVID-19: an opinion paper

The precocity and efficacy of the vaccines developed so far against COVID-19 has been the most significant and saving advance against the pandemic. The development of vaccines has not prevented, during the whole period of the pandemic, the constant search for therapeutic medicines, both among existing drugs with different indications and in the development of new drugs. The Scientific Committee of the COVID-19 of the Illustrious College of Physicians of Madrid wanted to offer an early, simplified and critical approach to these new drugs, to new developments in immunotherapy and to what has been learned from the immune response modulators already known and which have proven effective against the virus, in order to help understand the current situation.     

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.