Changes of Monophasic Action Potential Duration and Effective Refractory Period of Three Layers Myocardium of Canine during Acute

Summary： The effect of acute ischemia on the electrophysiological characteristics of the three layers myocardium of canine in vivo was investigated. Twelve canines were divided into two groups randomly： acute ischemia （AI） group and sham operation （SO） group. By using the monophasic action potential （MAP） technique, MAP and effective refractory period （ERP） of the three layers myocardium were measured by specially designed plunge needle electrodes and the transmural dispersion of repolarization （TDR） and transmural dispersion of ERP （TDE） were analyzed. The results showed that in the AI group, MAP duration （MAPD） was shortened from 201.67±21.42 ms to 169.50±13.81 ms （P〈0.05）, but ERP prolonged to varying degrees and TDE increased during ischemia. In the SO group, MAPD and ERP did not change almost. Among of the three layers myocardium of canine, MAPD was coincident in two groups. It was concluded that during acute ischemia, MAPD was shortened sharply, but there was no significant difference among of the three layers myocardium. The prolonged ERP was concomitant with increased TDE during acute ischemia, which may play an important role in the occurrence of arrhythmias induced by acute ischemia. These findings may have important implications in arrhythmogenesis.

Effects of Electric Stimulations Applied during Absolute Refractory Period on Cardiac Function of Rabbits with Heart Failure

The effects of electric currents applied during absolute refractory period （ARP） on the cardiac function of rabbits with heart failure due to myocardial infarction （MI）, and the safety of this method were investigated. Thirty rabbits were randomly assigned equally to 3 groups： sham-operated group, LV-anterior wall cardiac contractility modulation （LV-CCM） group, and septum-CCM （S-CCM） group. A thoracotomy was performed on all the rabbits. Electric pulses were delivered during the ARP on the anterior wall of left ventricle in CCM group and in the septum in S-CCM group, respectively. The left ventricular systolic pressure （LVSP） and maximum positive left ventricular pressure change （＋dp/dtmax）, heart rates, ventricular tachycardia, ventricular fibrillation were observed. It was found that, as compared with the baseline, LVSP, and ＋dp/dtmax were significantly increased, on average, by 15.2% and 19.5% in LV-CCM group （P〈0,05）, and by 8.5% and 10.8% in S-CCM group （P〈0.05）. LVEDP was significantly decreased and -dp/dtmx increased both in LV-CCM group and S-CCM group （P〈0.05）. CCM had no effect on heart rate and induced no arrhythmia in short time. It is concluded that electric currents delivered during the ARP could significantly enhance the contractility of myocardium safely, suggesting that CCM stimulation is a novel potent method for contractility modulation.

Effects of Electric Stimulations Applied During Absolute Refractory Period on Ventricular Muscle from Rabbits

Objectives To investigate the influences of electric signals applied during absolute refractory period (ARP) on the contractility of isolated papillary muscle from rabbits. Methods Papillary muscle was exercised from the right ventricle and was paced at 1 Hz. Biphasic square wave current pulse was delivered during the absolute refractory period (called CCM) in isolated, superfused, isometrically contractility rabbit papillary muscle. The peak tension (PT) of papillary muscle, as well as maximum positive tension change ( + dT/dtmax), were observed. Results Compared with the baseline, both PT and + dT/dtmax significantly increased during CCM stimulation by 18.2% and 21.4% respectively (P < 0. 05) . In addition, PT increased significantly with one or two beats following CCM signal application and reached a. new steady state level after a few beats. Once the CCM signals were turned off, the PT returned to the approximately baseline level ( P < 0. 05). Moreover, the effect of CCM on PT was dose - response to voltage. The obvious effect was at higher voltage. No effect was observed at lower voltage. Conclusions Electric signals delivered during the absolute refractory period can rapidly enhance the contractility of myocardium, which suggests that CCM signal is a novel potent method for contractility modulation.

Effects of Amiodarone on Transmural Dispersion of Ventricular Effective Refractory Periods across Myocardial Layers in the Normal and Hypertrophic Canine Heart

The effects of amiodarone on transmural dispersion of ventricular effective refractory periods （ERPs） in the normal and hypertrophic canine heart were investigated in vivo. By using the programmed stimulation protocol, the ERPs of epicardium （Epi）, midmyocardium （Mid） and endocardium （Endo） were measured by inserting specially-designed electrodes into the three myocardial layers before and after mainlining of amiodarone. No significant ERPs-dispersion was observed in the three layers before and after mainlining of amiodarone in the normal group. In contrast, ERPs of all the three layers were prolonged in the hypertrophic heart, while the ERPs-dispersion was reduced significantly after mainlining of amiodarone. The ERPs-dispersion was significantly increased in the hypertrophic heart but not in the normal heart using ＂long-short＂ and ＂short-long＂ interval stimulation technique. It was concluded that （1） the differences in ERPs-dispersion among the three layers were significant in hypertrophic heart, and differences were not significant in normal canine heart; （2） ERPs of each three-myocardial layers were significantly prolonged after using amioda- rone, but the ERPs-dispersion decreased in hypertrophic heart and （3） the programmed extrastimulus technique of ＂long-short＂ and ＂short-long＂ intervals increased the transmural ERPs-dispersion in the hypertrophic heart.

Effect of β_3-adrenoceptors on Ventricle Fibrillation Threshold and Effective Refractory Period in Rats With Heart Failure

Objectives To observe the effect of β3-Adrenoceptor （AR） on ventricle fibrillation threshold （VFT） and effective refractory period （ERP） in rats with heart failure. Methods Rats were randomized into control group and heart failure group. The expression of β3-ARmRNA was detected with RTPCR; The VFT, ERP, LVESP,LVEDP, ＋dp/dtmax and -dp/dtmax was measured at the same time with administration of BRL37344 （ 2 nmol / kg, β3- AR agonist）. Results ①Both the expression of β3-AR mRNA and the proportion increased in rats with heart failure in comparison with control rats （0.028 vs. 0.011 and 5.4% vs 1.2%, P 〈 0.05）;② ERP was longer in rats with heart failure than control group （70.5±5.5 ms vs 59.5±6.4ms, P 〈 0.05） and there was no difference of ERP in rats with heart failure with administration of BRL37344 （73.0±4.8 ms vs 70.5± 5.5 ms, P 〉0.05）; ③VFT was lower in rats with heart failure than control group（10.9±0.8 mv vs 30.5± 1.3 mv, P〈 0.05） and decreased obviously in rats with heart failure with administration of BRL37344 （7.1±0.6 mv vs 10.9±0.8 mv, P 〈 0.05） ; The decrease of VFT correlated with the effect on LVESP, ＋dp/ dtmax,-dp/dtmax of BRL37344 and the expression of β3-AR mRNA （correlation coefficient： 0.788, 0.708, 0.759, 0.787; P 〈 0.05）. Conclusions The expression of β3-AR mRNA of left ventricle was obviously increased in rats with heart failure, and activation of β3-AR had no effect on ERP but could decreased VFT which correlated with the effect of β3-AR on LVESP, ＋dp/dtmax, -dp/dtmax and the expression of β3-AR mRNA.

Effects of Electrical Stimulation During Absolute Refractory Period on Contraction and Relaxation of Cardiomyocytes from Normal Guinea - pigs

Objectives To investi-gate the effect of electrical stimulation during absolute refractory period on contraction and relaxation of ventricular myocytes from normal guinea - pigs. Methods The guinea - pig ventricular myocytes were obtained by enzyme digesting, and the extent of its contraction and relaxation and Ca2+ transient were recorded through the motion edge detection system. Results (1) The contracting extent of guinea - pig ventricular myocytes increased 15.45±6.48% , and the peak velocity of shorting (contraction) and the peak veloci ty of relengthening (relaxation) increased 15.97 ± 8.37% and 21. 63±8. 06% respectively (n = 10); (2) The extent of ventricular myocytes fluorescence ra tio(360/380) (F360/F380) increased 22. 55±9. 08%, and the peak velocity of ventricular myocytes F360 /F380 increased 36. 75 ± 9. 77% and 23. 62±4. 47% during shorting and relengthening respectively (n = 6) . Conclusions Appropriate electrical stimulation may strengthen the contracting and relaxing function of normal guinea - pig ventricular myocytes.

Influence of Selective Edge Removal and Refractory Period in a Self-Organized Critical Neuron Model

A simple model for a set of integrate-and-fire neurons based on the weighted network is introduced.By considering the neurobiological phenomenon in brain development and the difference of the synaptic strength,weconstruct weighted networks develop with link additions and followed by selective edge removal.The network exhibitsthe small-world and scale-free properties with high network effficiency.The model displays an avalanche activity ona power-law distribution.We investigate the effect of selective edge removal and the neuron refractory period on theself-organized criticality of the system.

Variation of repetitive cortical spreading depression waves is related with relative refractory period： a computational study

Cortical spreading depression （CSD） is an important experimental model for diseases such as stroke, epilepsy and migraine. Previous observations indicated that the amplitude and velocity of the typical direct current potential shift during repetitive CSD waves were varying. The recovery state of the tissue was found related with the variation of successive CSD waves. A computational model in this paper aimed to investigate the role of relative refractory period of CSD. This model simulated that continuous injection of KCI solution induced repetitive CSD waves. The first CSD wave often had a larger amplitude and faster velocity than those of the succeeding secondary waves. The relative refractory period lasted much longer than the recovery of ions turbulence. If the induction interval was long enough for recovery, a series of CSD waves would have the same profile asthe first one. In the relative refractory period, an early stimulation might lead to a late initiation of CSD, i.e., ＂haste makes waste＂. The amplitude and velocity of CSD waves were found increasing with the initiation interval and asymptotic to those of the first CSD wave. This study verified that the propagation dynamics of CSD waves is modulated by the relative refractory period. It suggested that the refractory period is critical for preventing undesirable CSD waves.

A Reevaluation of the Critical Membrane Potential of the Effective Refractory Period in Guinea Pig Ventricular Fibres

The traditional critical membrane potential (CMP), -55—-60mV, which corresponds to effective refractory period (ERP), was anew investigated in guinea pig ventricular muscle fibres. The electrical and contractile responses to the stimulus during repolarization of action potential (AP), particularly from+10 to -60 mV, were observed. One third of 35 tested cells displayed testing action potential (TAP) and local response at≥-54 mV when they were stimulated by testing pulses in 37℃ normal Tyrode’s solution. Potential level of TAP which occurred earliest was at -30 mV and that of local response which appeared earliest was at 0 mV during repolarization among 95 systematic tests. Most of the TAPs belonged to the slow response potential type. The ratio of TAP evoked at ≥-54 mV initial membrane potential (IMP) was as high as 86% when the experiment was carried out in 37℃ 1.5 mmol KC1/L Tyrode’s solution. In view of distribution of IMPs of TAPs, the CMP of ERP in guinea pig ventricular muscle fibres was

电生理适宜技术在经皮肾镜围术期快速康复中的应用研究

目的:探讨电生理适宜技术在经皮肾镜围术期快速康复中的应用价值。方法:回顾性分析2022年1月—2023年6月200例行经皮肾镜手术患者的临床资料,按术后干预方式不同分为2组,对照组术后进行常规治疗和护理,观察组在此基础上采用电生理适宜技术低频电刺激干预。比较2组不同时间VAS评分及术后疼痛评分、肠鸣音恢复时间、首次排气排便时间、术后住院天数。结果:2组术后第1次VAS评分差异无统计学意义(P=0.526);观察组术后第2次、第3次、第4次VAS评分均较对照组低(P<0.001);观察组术后首次通气时间、首次排便时间均短于对照组(P<0.001);2组术后第1次听诊肠鸣音差异无统计学意义(P=0.217),观察组术后第2次听诊肠鸣音次数较对照组多(P<0.001);观察组患者术后住院天数短于对照组(P=0.010)。结论:电生理适宜技术能有效预防术后切口疼痛,术后能做到早期下床活动,促进患者早日通气排便,预防术后腹胀的发生,促进患者快速康复,缩短患者术后住院时间,患者满意度高。

阿立哌唑治疗育龄期难治性精神分裂症的效果及对泌乳素的影响

目的探讨帕利哌酮联合阿立哌唑治疗育龄期难治性精神分裂症的效果及对泌乳素的影响。方法将80例育龄期难治性精神分裂症患者按照随机数字表法分为研究组和对照组,各40例。对照组患者给予帕利哌酮治疗,研究组患者给予帕利哌酮联合阿立哌唑治疗,两组患者均治疗8周。比较治疗前后两组患者临床症状评分、血清泌乳素水平、蒙特利尔认知评估量表评分、世界卫生组织生存质量测定量表简表评分,并比较两组患者临床疗效、不良反应发生率、治疗依从率、复发率以及再住院率。结果治疗后研究组患者阳性和阴性症状量表总分及各维度评分、血清泌乳素水平、复发率及再住院率低于对照组,治疗依从率、临床总有效率、蒙特利尔认知评估量表评分、世界卫生组织生存质量测定量表简表评分高于对照组(P<0.05或0.01)。两组患者不良反应总发生率没有明显差异(P>0.05)。结论帕利哌酮联合阿立哌唑治疗育龄期难治性精神分裂症,可显著改善病情,有效降低血清泌乳素水平,安全性高,值得推广。

基于双任务范式的驾驶分心研究

目的基于心理不应期这一双任务研究基本范式,围绕多模态这一研究重点、驾驶这一应用背景,探讨混合刺激模态下驾驶分心时反应机制。方法在实验室搭建模拟驾驶平台,招募40位被试进行实验;实验数据用重复测量方差分析方法进行分析。结果不同刺激模态组合下心理不应期效应的影响不同,但不支持反向串扰现象的存在。结论验证了视觉注意的执行控制理论及多重资源相关理论,为后续的深入研究和现实应用提供一定的帮助。

miR-208a在兔快速心房起搏模型中抑制心房电重构和结构重构的作用研究

目的通过建立快速起搏兔心房模型,探讨miR-208a在心房电重构和结构重构中的作用。方法40只新西兰大耳白兔随机分为4组:假手术组(SHAM组)、快速起搏组(RAP组)、快速起搏+agomiR-208a组(miR-208a组)和快速起搏+antagomiR-208a组(antmiR-208a组),每组各10只。起搏频率为600次/min,在程序刺激的0、4、8、12 h测定心房有效不应期(AERP)并计算AERP频率适应性。刺激结束后,处死动物,收集左心房组织,检测超氧化物歧化酶(SOD)活性、丙二醛(MDA)、活性氧(ROS)水平评估氧化应激;HE染色观察心房结构重构;采用RT-PCR法检测miR-208a RNA表达;采用Western blot法检测β-catenin表达。结果RT-PCR显示,RAP组miR-208a水平均低于SHAM组和miR-208a组(均P<0.05);与RAP组相比,antmiR-208a组中miR-208a水平明显降低(P<0.05)。与RAP组相比,miR-208a组AERP明显改善,而antmiR-208a组的结果相反;与RAP组相比,miR-208a组的AERP频率适应性升高,而antmiR-208a组降低(P<0.05)。HE染色显示,RAP组心肌纤维排列不规则,部分纤维溶解并断裂,与RAP组比较,antmiR-208a组的心肌组织病理改变更加显著,而miR-208a组的心肌组织病理改变得到改善。与RAP组相比,miR-208a组心肌组织中MDA和ROS水平均降低,SOD活性升高(均P<0.05);antmiR-208a组的MDA和ROS水平均升高,SOD活性降低(均P<0.05)。Western blot显示,RAP组β-catenin蛋白表达高于SHAM组(P<0.05);与RAP组相比,miR-208a组中β-catenin蛋白表达降低,而antmiR-208a组升高(均P<0.05)。结论miR-208a可以改善心房快速起搏模型兔中心房的电重构和结构重构,并减轻心房的氧化应激水平,这些作用可能与β-catenin信号传导途径的抑制有关。

葛根素对豚鼠心肌细胞动作电位及有效不应期的影响

目的 观察葛根素对豚鼠乳头肌动作电位及有效不应期的影响 ,以探讨其抗心律失常的作用机制。方法 采用标准玻璃微电极细胞内记录技术。结果 ①葛根素 0 0 0 5 ,0 0 1,0 0 15mmol·L-1能使豚鼠心室肌细胞动作电位复极5 0 %时程 (APD50 )和复极 90 %时程 (APD90 )明显延长 ,APD50分别由 ( 176 4 3± 5 1 3 7)ms延长至 ( 192 86± 60 82 )ms(n=7,P <0 0 5 ) ,( 2 0 0 71± 63 0 8)ms和 ( 2 0 7 71± 65 4 5 )ms(n =7,P <0 0 1) ;APD90 分别由 ( 2 0 0 71± 5 9 75 )ms延长至 ( 2 2 1 4 3± 70 4 6)ms(n =7,P <0 0 5 ) ,( 2 3 5 0 0±5 8 88)ms和 ( 2 4 0 0 0± 5 8 4 5 )ms(n =7,P <0 0 1) ,并且这种延长呈现量效关系。②采用 0 2 ,0 5 ,1,2 ,4Hz频率的方波刺激 ,发现在 0 0 1mmol·L-1时葛根素延长心肌细胞APD50 有明显的非逆向频率依赖性。③使用双脉冲刺激发现在 0 0 1mmol·L-1时葛根素能明显延长心肌细胞的有效不应期 ,由 ( 98 0 0± 16 4 3 )ms延长至 ( 168 0 0± 13 0 4 )ms(n =5 ,P <0 0 1)。结论 葛根素能延长心肌细胞APD50 和APD90 以及心肌细胞有效不应期 ,其抗心律失常的机制源于此作用。

幽门螺杆菌感染对儿童功能性消化不良胃电参数的影响

目的通过多导胃电图方法探讨幽门螺杆菌(HP)感染与功能性消化不良(FD)的关系。方法 163例FD患儿,包括103例HP感染(A组)、60例无HP感染(B组),同时选22例无消化道症状患儿为对照组(C组)。3组均进行多导胃电图检测,包括正常慢波百分比(N%)、胃动过缓百分比(B%)、胃动过速百分比(T%)、胃动节律不齐百分比(A%),胃电频率及功率包括主频率(DF)及主功率(DP),餐后/餐前胃电主功率比(P/R),分析胃电描记数据。并对A组中84例治疗后HP转阴患儿的治疗前及治疗后胃电参数进行比较。结果 A组与B组比较,不同慢波频率的百分比差异餐后较餐前明显,餐前餐后DF、DP的变化均不明显。84例HP转阴患儿治疗前后比较,不同慢波频率的百分比改善不明显,但餐前餐后DF、DP及P/R改善均较明显。结论多导胃电图显示HP治疗对改善HP感染的FD患儿餐后症状有很大益处。

甲状腺素诱发房性和室性心律失常的实验研究

目的:应用单相动作电位技术,通过比较甲亢状态下心房肌和心室的电生理特性的改变来探讨发生房性心律失常的可能机制。方法:24只日本大耳白兔随机分为对照组(12只)和甲状腺素组(12只)。甲状腺素组腹腔注射左旋甲状腺素(L-T4)1 mg/(kg.d)复制甲状腺机能亢进模型。对照组给予等体积的生理盐水腹腔注射。两组动物各自随机分为心房组和心室组进入实验(每组6只)。采用单相动作电位记录技术记录四组心房肌和心室肌电生理指标的变化,同时程序刺激诱发房性和室性心律失常。结果:心房肌和心室肌单相动作电位时程(MAP90)、有效不应期(ERP)和ERP/MAP90比值均较对照组明显缩短,具有显著性差异;但是在给予程序性电刺激时,甲状腺素组的房性心律失常的发生率明显高于对照组;而两组间室性心律失常的发生率差异无显著性。结论:甲亢状态下房性心律失常比室性心律失常易于诱发,可能与心房肌单相动作时程和有效不应期非同步性缩短的电异质性,以及和心房解剖结构存在的各向异性密切相关。

当归A_3部位对心肌生理特性和动作电位的影响

目的 研究A3 部位对离体心肌生理特性和心室乳头肌动作电位的影响。方法 采用常规离体器官实验法记录右房自搏频率、心肌收缩力和功能性不应期 ;采用标准细胞内微电极技术记录动作电位 (AP)。结果 A3 部位 (10～ 16 0mg·L-1)能显著抑制右心房的自搏频率 ,16 0mg·L-1时可使右心房停搏 ;它剂量依赖性地降低左心房的收缩力 ,IC50 为5 2 3mg·L-1;它还明显延长功能性不应期 (FRP) ,10 0mg·L-1时 ,使FRP从给药前的 10 6ms延长至 130ms ;A3 部位剂量依赖性地降低动作电位振幅 (APA) ,缩短复极 2 0 %时程 (APD2 0 )和复极 90 %时程 (APD90 ) ,对静息电位 (RP)无影响。结论 当归A3 部位对心肌生理特性和动作电位的作用可能与其阻Ca2 + 、Na+ 内流和促K+

视觉发育敏感期单眼形觉剥夺大鼠视觉电生理及视皮质超微结构研究

目的:检测视觉发育敏感期单眼形觉剥夺大鼠视觉电生理功能,并观察其视皮质超微结构。方法:健康14日龄SD大鼠20只,随机分为两组,实验组及对照组各10只。实验组大鼠缝合封闭单侧眼,制作单眼形觉剥夺动物模型。与对照组在同等自然光照环境下饲养至45日龄。分别对两组鼠进行电生理检测,并使用透射电镜观察两组大鼠视皮质的超微结构。结果:正常大鼠F-VEP呈现典型的NPN波形,P1波峰潜时短,波峰陡直。形觉剥夺大鼠F-VEP检测结果:P1波峰潜时明显延长,波峰显著降低。电镜观察单眼形觉剥夺动物视皮质神经元的超微结构发现:形觉剥夺动物视皮质中神经元的超微结构受到破坏。结论:单眼形觉剥夺可以影响大鼠视觉电生理的变化,使P波峰的潜时延长,振幅降低,这一改变是形觉剥夺性弱视视觉生理功能改变的体现;单眼形觉剥夺可以引起大鼠视皮质神经元超微结构破坏,这一改变是形觉剥夺性弱视的形态学基础。

SD大鼠房颤模型的建立

目的研究一种发病机制,病理改变与临床接近且造模周期较短的大鼠房颤模型制备方法与技术。方法大鼠连续给药,经尾静脉注射乙酰胆碱-氯化钙混合液,每次给药后记录房颤持续时间。寻找能诱发稳定房颤的给药剂量和给药时间。电生理学方法观察正常和模型大鼠心房不应期的变化。结果CaCl210 mg/mL,乙酰胆碱66μg/mL模型大鼠从第4 d起房颤时间缓慢增长,7 d后趋于稳定。与正常组相比,模型大鼠心房肌ERP显著缩短(59.3 ms±5.8 ms)。结论CaCl210 mg/mL+乙酰胆碱66μg/mL混合液连续给予7 d诱导产生的大鼠房颤模型,其电生理学的病理变化与临床房颤相似,适用于化合物抗房颤活性筛选研究。

心力衰竭犬跨室壁心肌复极时间和不应期离散度的致心律失常机制研究

目的:从复极和不应期两个角度,观察不同部位起搏对心力衰竭犬三层心肌跨室壁复极和不应期离散度的影响及其可能的致心律失常机制。方法:正常犬8只和心力衰竭模型犬5只,模拟临床上充血性心力衰竭患者接受心脏再同步治疗的情况,分别从右心室心内膜、左心室心外膜和双心室发放刺激,在体记录和比较犬三层心肌的单相动作电位时程、不应期及其跨室壁离散度。在心力衰竭犬组,给予维拉帕米进行干预并重复上述实验。结果:心力衰竭犬三层心肌的动作电位时程与不应期均有延长,中层心肌动作电位时程延长最明显[(279.30±54.81)ms vs(270.03±57.58)ms,P<0.01],跨室壁复极离散显著增大[(29.80±25.67)ms vs(20.60±12.65)ms,P<0.01],不应期离散有所减小[(29.21±15.83)ms vs(31.25±20.83)ms,P>0.05];左心室心外膜和双心室刺激增加跨室壁复极离散度,但对跨室壁不应期离散度无明显影响;维拉帕米能在一定程度上延长中层和心外膜下心肌的动作电位时程与不应期,减小跨室壁复极和不应期离散[心力衰竭犬给予维拉帕米后(24.50±15.18)msvs正常犬(31.25±20.83)ms,P<0.05]。结论:心力衰竭犬跨室壁复极离散增大、不应期离散减小;维拉帕米减小心力衰竭犬跨室壁复极与不应期离散;左心室心外膜参与的起搏方式对心肌不应期无明显影响,但增大跨室壁复极离散,且这一效应不能被维拉帕米矫正。