Promising application of a new ulnar nerve compound muscle action potential measurement montage in amyotrophic lateral sclerosis:a prospective cross-sectional study

Previous studies have shown that ulnar nerve compound muscle action potential recorded by the conventional“belly-tendon”montage does not accurately and completely reflect the action potential of the ulnar nerve dominating the abductor digiti minimi muscle due to the effects of far-field potentials of intrinsic hand muscles.A new method of ulnar nerve compound muscle action potential measurement was developed in 2020,which adjusts the E2 electrode from the distal tendon of the abductor digitorum to the middle of the back of the proximal wrist.This new method may reduce the influence of the reference electrode and better reflect the actual ulnar nerve compound muscle action potential.In this prospective cross-sectional study,we included 64 patients with amyotrophic lateral sclerosis and 64 age-and sex-matched controls who underwent conventional and novel ulnar nerve compound muscle action potential measurement between April 2020 and May 2021 in Peking University Third Hospital.The compound muscle action potential waveforms recorded by the new montage were unimodal and more uniform than those recorded by traditional montage.In the controls,no significant difference in the compound muscle action potential waveforms was found between the traditional montage and new montage recordings.In amyotrophic lateral sclerosis patients presenting with abductor digiti minimi spontaneous activity and muscular atrophy,the amplitude of compound muscle action potential-pE2 was significantly lower than that of compound muscle action potential-dE2(P<0.01).Using the new method,damaged axons were more likely to exhibit more severe amplitude decreases than those measured with the traditional method,in particular for patients in early stage amyotrophic lateral sclerosis.In addition,the decline in compound muscle action potential amplitude measured by the new method was correlated with a decrease in Revised Amyotrophic Lateral Sclerosis Functional Rating Scale scores.These findings suggest that the new ulnar nerve compound muscle action potential measurement montage reduces the effects of the reference electrode through altering the E2 electrode position,and that this method is more suitable for monitoring disease progression than the traditional montage.This method may be useful as a biomarker for longitudinal follow-up and clinical trials in amyotrophic lateral sclerosis.

Clinical application of electrically evoked compound action potentials

ECAPs are the summary of multiple neurons’ spikes which could be recorded by a bidirectional stimulation-recording system via the cochlear implant,with the artifact elimination paradigms of forward-masking subtraction paradigm or alternating polarity paradigm.Three kinds of FDA approved cochlear implants support ECAP testing.This article is to summarize the clinical application of ECAP lest.ECAP test after insertion of electrode during implant operation has been widely used during cochlear implant surgery.In recent years.ECAP thresholds are also used to estimate the T levels and C levels helping programming.However,correlation between ECAP thresholds and psychophysical thresholds is affected by many factors.So far,ECAPs cannot yet be a good indicator of post-operative hearing and speech performance.

A Study of Compound Action Potentials in Current-Coupled Tracts: the General Case

In this paper, the authors investigate compound action potentials formed when the underlying tract's axons have current-mediated coupling amongst themselves, and no field-mediated coupling. The key finding of the paper is that, for the case of biophysically inhomogeneous axon tracts, the compound action potential is governed by a Hodgkin-Huxley like equation itself in certain cases. The paper extends an earlier result for the identical axon case.

健康豚鼠不同直径刺激电极圆窗ECAP比较分析

目的比较分析不同直径刺激电极对健康豚鼠圆窗电诱发复合动作电位(electrically evoked auditory nerve compound action potentials,ECAP)的影响。方法选取健康豚鼠12只(24耳),随机分为A组和B组,每组6只(12耳),A组使用直径为0.7mm的银球电极,B组使用直径为1mm的银球电极。吸入麻醉后打开听泡,刺激电极正极置于圆窗膜,在电刺激条件下通过体表电极记录ECAP波形,比较两组ECAP引出率、阈值、幅值、潜伏期;总和电位(electrically evoked summating potentials,ESP)幅值、潜伏期。结果刺激电极直径愈大,ESP阈值愈小,潜伏期愈长,差异有统计学意义(P=0.021,P<0.05)。但刺激电极直径不同时ECAP的引出率、阈值、幅值与潜伏期及ESP幅值、阈值无显著性差异。结论全麻下豚鼠圆窗ECAP可以稳定地记录到,其引出率、阈值与刺激电极直径大小无明显相关性。与直径为1 mm的银球电极相比,使用直径为0.7 mm的银球电极可以更快引出ESP,但刺激电极直径为1 mm时ECAP、ESP波形分化更好。

Effect of applied electric fields on supralinear dendritic integration of interneuron

Evidences show that electric fields(EFs)induced by the magnetic stimulation could modulates brain activities by regulating the excitability of GABAergic interneuron.However,it is still unclear how and why the EF-induced polarization affects the interneuron response as the interneuron receives NMDA synaptic inputs.Considering the key role of NMDA receptor-mediated supralinear dendritic integration in neuronal computations,we suppose that the applied EFs could functionally modulate interneurons’response via regulating dendritic integration.At first,we build a simplified multi-dendritic circuit model with inhomogeneous extracellular potentials,which characterizes the relationship among EF-induced spatial polarizations,dendritic integration,and somatic output.By performing model-based singular perturbation analysis,it is found that the equilibrium point of fast subsystem can be used to asymptotically depict the subthreshold input–output(sI/O)relationship of dendritic integration.It predicted that EF-induced strong depolarizations on the distal dendrites reduce the dendritic saturation output by reducing driving force of synaptic input,and it shifts the steep change of sI/O curve left by reducing stimulation threshold of triggering NMDA spike.Also,the EF modulation prefers the global dendritic integration with asymmetric scatter distribution of NMDA synapses.Furthermore,we identify the respective contribution of EF-regulated dendritic integration and EF-induced somatic polarization to an action potential generation and find that they have an antagonistic effect on AP generation due to the varied NMDA spike threshold under EF stimulation.

Effects of ranitidine on contraction and action potentials in normal and potassium depolarized isolated papillary muscles of the guinea pig

The purpose of these experiments was to investigate the possible ionicbases for ranitidine （Ran） in isolated papillary muscles of the guinea pig.Ran,when the concentration was below 300μmol/L,had no influence on contraction ofnormal muscles and only above 0.3 mmol/L,it showed weak negative inotropic ef-fect.The contractile activity elicited by histamine in potassium depolarized mus-cles was depressed by Ran markedly and dose-dependently.The IC50 of Ran was0.273μmol/L.This depressant effect was reversed by an elevation of externalCa2+concentration to 7.7mmol/L.The contraction induced by isoproterenol inpotassium depolarized preparations was not altered by Ran.Ran at theconcentrations of 1,10 and 100μmol/L failed to show influences on fast actionpotentials.However,Ran at 0.5μmol/L time-dependently inhibited slow action po-tentials.It is concluded that the ionic mechanism of Ran might be attributed toantagonized H2 receptor of myocardium which in turn decreases Ca2+ inward cur-rent.

THE INFLUENCE OF SAPONINS OF PANAX QUINQUEFOLIUM LEAF AND STEM ON THE SLOW ACTION POTENTIALS IN MYOCARDIUM

The effects of Saponins of Panax Quinquefolium Leaf and Stem(SPQLS)were evaluatedin the rabbit sinus node and in the guinea pig papillary muscles both showing slow responses in high[k+].and being exposed to 0.3 μmol/L verapamil using conventional microelcctrode technique.Inthe sinus node, SPQLS 100 mg/L decreased the APA and Vmax.At the concentration of 200 mg/L,in addition to further depressing the upotroke,SPQIS decreased the SP4,shortened the APD and prolonged the SCL.In the guinea Pig papillary muscle,SPQLS shortened the APD and decreased theAPA as well as Vmax in high[k+3].When verapamil was exposed to the normal Tyrode's solution,SPQLS depressed the upstroke without-affecting the APD in the guinea pig papillary muscle.Thesefindings suggest that SPQLS exerted a blockade effect on the transmembrane Ca2+ influx and Na+ influx in myocardium.

EFFECTS OF DISMERINONE ON HIGH K~＋ DEPOLARIZED SLOW RESPONSE ACTION POTENTIALS IN GUINEA PIG PAPILLARY MUSCLES

The effects of dismerinone (DMR), a derivative of milrinone, on high K+ depolarized slow response action potentials (APs) and intracellular cAMP levels were studied in guinea pig papillary muscles. DMR induced slow APs in high K+ depolorized guinea pig papillary muscles and increased APA, Vmaxand APD50 of the slow APs in dose dependent way ; cAMP levels in same preparations were elevated by DMR. These effects of DMR are similar to isoprenaline (ISO). Bead adrenocepter blocker propranolol had no influence on DMR effect. Overall, the results from this study suggested that effects of DMR were not related to Beta adrenocepter, and might be related to its inhibiting phosphodiesterase Ⅲ(PDE Ⅲ) action.

基于AP-42方法的2019年我国加油站VOCs排放分析

加油站成品油销售过程产生的VOCs由于物种活性高、臭氧生成潜势大,一直是我国大气O_(3)污染防治的重点污染源之一.为了解我国不同地区加油站VOCs污染特征和排放强度,利用美国环境保护部(USEPA)人为源空气污染物排放清单编制技术手册中推荐的加油站VOCs排放测算方法(AP-42方法),结合2019年我国31个省(自治区、直辖市)油品消费量情况以及直辖市、省会(首府)城市的环境地理信息等(不包括港澳台地区数据,下同),定量测算了2019年我国各省份加油站VOCs排放因子和排放量,研究了不同情景下我国加油站VOCs的减排潜力.结果表明:(1)我国各直辖市、省会(首府)城市加油站汽油VOCs排放因子的平均值为2.41 kg/t,但差异性较大,海口市最高(3.46 kg/t),拉萨市最低(1.47 kg/t),二者相差1.35倍.(2)无控制情形下,2019年我国加油站VOCs排放量约为41.48×10^(4)t,主要集中在南方部分地区(广东省、江苏省、湖北省、四川省、湖南省、浙江省、安徽省、福建省)和地域人口大省(河南省、山东省和辽宁省),占加油站VOCs排放总量的64.54%.(3)我国加油站VOCs减排潜力仍十分巨大,当汽油油气回收效率在90%以上时,加油站VOCs排放量将降到5.44×10^(4)t以下;差异化的管控措施情景下,我国加油站VOCs排放量也将下降25.07×10^(4)~30.23×10^(4)t.研究显示,我国加油站VOCs排放地域性差异较大,有针对性的管控措施有助于加油站VOCs减排.

Effects of 2-[p-(Dimethylamino)Styrl] PyridineMethiodide on Slow Response Action Potentialand Slow lnward Current of Guinea PigPapillary Muscles

The effects of 2-[p-(Dimethylamino)styryl] pyridine methiodide(DSPM)on slow response action potential(SRAP)and slow inward current(Isi) of guinea pig papillary muscles were studied by intracellular microelectrodes and voltage clamp techniques.The APA and V_(max) of SRAP induced by high K￣+were decreased after 50 min of perfusion with DSPM solu- tion. Isi was suppressed from a peak value of8.8± 1.6μA to 5.7± 1.8μA, The results indicated that DSPM has a selective blocking effect on calcium channel.

Character of diaphragm compound muscle action potential and phrenic nerve conduction time in patients with obstructive sleep apnea-hypopnea syndrome

BACKGROUND： Both hypoxia and.carbon dioxide retention can damage phrenic nerve and muscle conduction, as well as diaphragm function. Diaphragm compound muscle action potential and phrenic nerve conduction time are reliable indicators for measuring phrenic nerve and diaphragm function. OBJECTIVES： To verify the hypothesis that changes of phrenic nerve conduction time （PNCT） and diaphragm compound muscle action potential （CMAP） in obstructive sleep apnea-hypopnea syndrome （OSAHS） patients might contribute to the decline of phrenic nerve and diaphragm function. PNCT and CMAP were measured with multipair esophageal electrodes combined with unilateral magnetic stimulation. DESIGN, TIME AND SETTING： Case controlled study. The experiment was carried out in Guangzhou Institute of Respiratory Disease, Guangzhou MediCal College, from June 2005 to April 2006. PARTICIPANTS： Twenty seven OSAHS patients and eight primary snoring subjects from Guangzhou Institute of Respiratory Disease, Guangzhou Medical College were recruited and all subjects were diagnosed by polysomnography （PSG）. Sixteen healthy, non-snoring subjects in the hospital for medical examination during the same time period were selected as the control group. METHODS： Esophageal electrodes, made by Guangzhou Institute of Respiratory Disease, combined with unilateral magnetic stimulation, were used to measure PNCT and CMAP of all subjects. PNCT was defined as the time from stimulation artifact to the onset of CMAP and diaphragm CMAP amplitude was measured from peak to peak. Oxygen desaturation index and apnea-hypopnea index were measured using PSG, and their relevance to PNCT and CMAP were analyzed. PNCT and CMAP in five OSAHS patients were repeatedly measured after effective nasal continuous positive airway pressure treatment for more than 2 months. MAIN OUTCOME MEASURES： （1） PNCT and diaphragm CMAP of subjects in each group. （2） Relevance of oxygen desaturation index and apnea-hypopnea index to PNCT and CMAP. （3） Changes of PNCT and CMAP of OSAHS patients before and after treatment. RESULTS： All subjects were included in the analyzed results. （1） PNCT of the OSAHS group was significantly longer compared to that of the control and primary snore groups, while CMAP of the OSAHS group was significantly lower （P 〈 0.05）. （2） PNCT and CMAP recorded from both sides correlated significantly with oxygen desaturation index and with apnea-hypopnea index （P 〈 0.01 ）. （3） PNCT shortened significantly after effective nasal continuous positive airway pressure treatment for more than 2 months （ P 〈 0.05）. CONCLUSION： Prolongation of PNCT and decrease of CMAP might contribute to the decline of phrenic nerve and diaphragm function caused by repeated nocturnal hypoxia and carbon dioxide retention. The impairment of the phrenic nerve might also decrease diaphragm function.

The optimal distance between two electrode tips during recording of compound nerve action potentials in the rat median nerve

The distance between the two electrode tips can greatly influence the parameters used for record- ing compound nerve action potentials. To investigate the optimal parameters for these recordings in the rat median nerve, we dissociated the nerve using different methods and compound nerve action potentials were orthodromically or antidromically recorded with different electrode spac- ings. Compound nerve action potentials could be consistently recorded using a method in which the middle part of the median nerve was intact, with both ends dissociated from the surrounding fascia and a ground wire inserted into the muscle close to the intact part. When the distance be- tween two stimulating electrode tips was increased, the threshold and supramaximal stimulating intensity of compound nerve action potentials were gradually decreased, but the amplitude was not changed significantly. When the distance between two recording electrode tips was increased, the amplitude was gradually increased, but the threshold and supramaximal stimulating intensity exhibited no significant change. Different distances between recording and stimulating sites did not produce significant effects on the aforementioned parameters. A distance of 5 mm between recording and stimulating electrodes and a distance of 10 mm between recording and stimulating sites were found to be optimal for compound nerve action potential recording in the rat median nerve. In addition, the orthodromic compound action potential, with a biphasic waveform that was more stable and displayed less interference （however also required a higher threshold and higher supramaximal stimulus）, was found to be superior to the antidromic compound action potential.

INTRINSIC FLUORESCENCE CHANGES IN NERVE TERMINALS,EVOKED BY ACTION POTENTIALS,ARE MODULATED BY KREBS CYCLE SUBSTRATES

Electrical stimulation of the mammalian neurohypophysial infundibular stalk evokes the entry of Nat and Ca^(2+) into the neurosecretory terminals during the action potential.These events,in turn,increase intracellular Ca^(2+) and activate NaK-and Ca-ATPases,prompting the mitochondria to increase oxidative phosphorylation which can be monitored by recording the changes in FAD and NADHfluorescence.This paper reflects our efforts to determine whether or not modulating the capacity of mitochondria to produce ATP,by changing the concentrations of two important substrates of the Krebs cycle of the nerve terminal mitochondria,pyruvate and glucose,has an effect on the intrinsicfluorescence changes triggered by action potential stimulation.

Proper Understanding of the Nerve Impulses and the Action Potential

Neurologists define the transmission of nerve impulses across the membranes of the neural cells as a result of difference in the concentration of ions while they measured an electric potential, called as an action potential, which allows the propagation of such nerve impulses as electrical signals. Such measurements should guide them to a logical explanation of the nerve impulses as electric charges driven by the measured action potential. However, such logical conclusion, or explanation, is ignored due to a wrong definition of the flow of electric charges as a flow of electrons that cannot pass through neural networks. According to recent studies, electric charges are properly defined as electromagnetic (EM) waves whose energy is expressed as the product of its propagating electric potential times their entropy flow which is adhered to the flow of such energy. Such definition matches the logical conclusion of the nerve impulses as electric charges, as previously explained, and defines the entropy of the neural network, measured by Ammeters, in Watt or Joule/Volt. The measured entropy represents a neurodiagnostic property of the neural networks that measures its capacity to allow the flow of energy per unit action potential. Theoretical verification of the innovative definition of nerve impulses is presented by following an advanced entropy approach. A proper review of the machine records of the stimulating electric charges, used in the diagnosis of the neural networks, and the stimulated nerve impulses or stimulated responses, represents practical verifications of the innovative definitions of the electric charges and the nerve impulses. Comparing the functioning of the thermoelectric generators and the brain neurons, such neurons are defined as thermoelectric generators of the electric nerve impulses and their propagating, or action, potential.

基于改进人工势场法的AUV全局路径规划

目的为了解决AUV(autonomous underwater vehicle)在传统人工势场法路径规划过程中存在的碰撞、目标不可达和局部极小值等问题,方法提出一种基于改进人工势场法(improved artificial potential field,IAPF)的AUV全局路径规划算法。首先为解决引力过大导致的碰撞问题,引入作用阈限制目标点的吸引力;然后在斥力场添加距离修正因子修正斥力函数,防止目标点离障碍物过近时,由于斥力大于引力引起目标不可达现象,同时考虑到障碍物大小的不等性会影响斥力的作用范围,对障碍物的最小安全距离进行修改;最后在此基础上添加外力,利用外力和势场力的共同作用使AUV沿切线方向行驶,从而摆脱局部极小点或陷阱区域。结果仿真实验结果表明,本文算法能够规划出一条最优路径,与同类算法相比,本文算法运行时间短,成功率高。结论本文提出的基于改进人工势场法的AUV全局路径规划算法,通过引入作用阈、距离修正因子、最小安全距离修正以及外力作用,有效解决了传统人工势场法在AUV路径规划中存在的碰撞、目标不可达和局部极小值等问题。

多部位肌肉面神经电图检测对贝尔麻痹患儿面神经功能及预后的评估价值

目的探讨面神经电图(ENoG)检测多块面肌方法在贝尔麻痹(BP)患儿面神经功能评估及早期预测预后中的价值。方法选取2020年6月至2022年9月在昆明医科大学附属儿童医院诊治的90例BP患儿,首诊时应用ENoG检测额肌、鼻肌、口轮匝肌、上眼轮匝肌及下眼轮匝肌等5块面肌的ENoG值及复合肌肉动作电位(CMAP)波幅,并采用House Brackmann分级系统(HBGS)对患儿的面神经功能进行评估,随访至完全恢复或至首诊后6个月,通过HBGS再次评估患儿的面神经功能。分析比较不同面肌的ENoG值在各年龄组(婴幼儿组、学龄前儿童组、学龄儿童组)及各预后组(完全恢复组、不完全恢复组)间的差异,以及与首诊HBGS评级的相关性。绘制受试者工作特征曲线并计算曲线下面积(AUC),以评估早期不同面肌的ENoG值对BP患儿预后的价值。结果首诊时患儿各部位ENoG值越低,则对应的首诊HBGS评级越高(P<0.05);鼻肌、上眼轮匝肌及下眼轮匝肌表现更显著(P<0.01)。首诊时的鼻肌、上眼轮匝肌及下眼轮匝肌的ENoG值显示,完全恢复组的秩平均值高于不完全恢复组(P<0.05);首诊时鼻肌、上眼轮匝肌及下眼轮匝肌的ENoG值可用于评估BP患儿的预后,AUC值分别为0.732、0.695及0.796(P<0.05);将上眼轮匝肌与鼻肌ENoG值联合、上眼轮匝肌与下眼轮匝肌ENoG值联合、下眼轮匝肌与鼻肌ENoG值联合,准确性进一步提升,AUC分别为0.740、0.799及0.806(P<0.01);首诊HBGSⅡ~Ⅲ级患儿的预后明显好于Ⅳ~Ⅴ级患儿(P<0.01)。结论BP发病初期鼻肌、上眼轮匝肌及下眼轮匝肌的ENoG值与HBGS评级一样可反映患儿病情的严重程度,较低的ENoG值提示BP可能恢复不完全,增加ENoG面肌检测部位可提高BP患儿预后评估的准确性。

依势而为:政治势能何以转化为乡村治理效能?——以R村由“后进村”向“示范村”蝶变为例

乡村治理是国家治理的重要方面,也是推进乡村振兴的基本保障。将“政治势能”概念引入乡村治理场域进行动态路径剖析发现,R村通过“依势而为”的行动路径推动政治势能经由“酝酿趋势—构建权势—扩大声势—明确定势—实现借势”的演进逻辑转化为乡村治理效能,实现了由“后进村”向“示范村”的蝶变,其中的关键是“党的领导在场”,彰显了具有中国特色的“政党统合社会”制度逻辑,在理论上拓宽了“政治势能”的内涵和解释范畴,在实践上为国家治理制度优势转化提供可行进路。

耳蜗电图SP/AP面积比在梅尼埃病诊断中的应用研究

目的：分析比较耳蜗电图（electrocochleography,ECoch G）中总和电位（summating potential,SP）与动作电位（action potential,AP）的幅度比和面积比两种方法在梅尼埃病（Meniere’s disease,MD）诊断中的应用价值。方法：样本总量为96名成人受试者（共测试123耳）。将其分为3组：对照组由56名听功能正常的受试者组成（共测试76耳）,确诊MD组25人（单耳21人,双耳4人,共测试29耳）;疑似MD组15人（单耳12人,双耳3人,共18耳）。将对照组的SP/AP幅度比与面积比的95%参考值上限作为阳性参考值,分别计算确诊MD组和可疑MD组的振幅比和面积比阳性率,比较两种方法阳性率的差异性及统计学意义。结果：对照组所得SP/AP幅度比95%参考值范围为：0.01～0.32,以〉0.32为阳性标准;SP/AP面积比95%参考值范围为：0.68～1.82,以〉1.82为阳性标准。确诊MD组中,幅度比的阳性检出率为14.29%（15/105）,面积比的阳性检出率为25.71%（27/105）,面积比阳性率高于振幅比阳性率（χ^2=6.050,P=0.014）。可疑MD组中,幅度比阳性率为16.67%（3/18）;面积比阳性率为77.78%（14/18）。两者阳性率差异有统计学意义（χ^2=9.091,P=0.003）,其面积比阳性率高于振幅比阳性率。结论：同SP/AP幅度比相比较,面积比在梅尼埃疾病的诊断中更具有优势。

环状RNA mmu_circ_0005019影响小鼠心肌细胞钙激活钾通道电流及动作电位

目的 探索环状RNA mmu_circ_0005019调控小电导钙激活钾(small-conductance calcium-activated potassium, SK)通道蛋白亚基SK3编码基因Kcnn3的表达,以及对小电导钙激活钾通道电流(IK,Ca)和动作电位时程(action potential duration, APD)的影响。方法 在小鼠HL-1细胞中分别构建mmu_circ_0005019过表达和干扰模型,分为过表达组(n=3)、空质粒组(n=3)、干扰1组(n=3)、干扰2组(n=3)、对照组(n=3),通过RT-qPCR、Western blot分析mmu_circ_0005019调节Kcnn3表达的分子机制,应用膜片钳技术电流钳模式记录全细胞的IK,Ca,并用电压钳模式记录APD。结果 成功构建了环状RNA mmu_circ_0005019过表达和干扰的HL-1细胞模型。过表达组的Kcnn3基因表达与空质粒组相比明显上调(P<0.05);干扰1组和干扰2组的Kcnn3基因表达与对照组相比均明显下调(P<0.05)。电生理发现过表达mmu_circ_0005019增加了HL-1细胞IK,Ca电流密度,APD显著缩短;相反,干扰mmu_circ_0005019减少了IK,Ca电流密度,APD显著延长。结论 mmu_circ_0005019可以上调小鼠HL-1细胞Kcnn3的表达水平,从而改变IK,Ca和APD,提示环状RNA mmu_circ_0005019可能在房颤发生中起到促进作用。

六价铬对牛蛙心脏、骨骼肌和坐骨神经干生理功能的影响

【目的】从电生理学角度研究六价铬对牛蛙心脏、腓肠肌和坐骨神经干动作电位的影响,探讨六价铬的毒性作用机制。【方法】将不同浓度重铬酸钾溶液通过腹腔注射和离体心脏灌流法处理牛蛙心脏,测定六价铬对在体和离体心脏心率和收缩力的影响。用重铬酸钾溶液浸润好的纱布包裹腓肠肌,测定腓肠肌收缩力变化。采用细胞外电极引导法,测定六价铬对坐骨神经干动作电位传导速度的影响。【结果】结果显示:重铬酸钾对心率和收缩力具有抑制作用,机制分别与六价铬抑制T型钙通道活性和L型钙通道活性有关;然而1 mg/L铬对在体蛙心作用15 min至30 min后,心率增加,可能是“毒物兴奋效应”所致;0.001 mg/L至10 mg/L六价铬对腓肠肌收缩力具有浓度依赖性增强作用,表现为正性变力效应,可能是“毒物兴奋效应”的结果;100 mg/L六价铬抑制了腓肠肌收缩力,表现为负性变力效应,机制与六价铬对兰尼碱受体(Ryanodine receptor,RyR)的抑制作用有关;六价铬以质量浓度和时间依赖性降低了神经干动作电位传导速度,机制与六价铬对电压门控Na+通道产生的失活作用有关。【结论】六价铬对心肌、骨骼肌和神经均具有毒性作用,结果可为六价铬的毒性作用研究提供一定的电生理实验依据。