丹参酮A磺酸钠对家兔在体心脏单相动作电位影响的研究

丹参酮A(Tashinone A)是从唇形科植物丹参的干燥根及根茎中提取出的脂溶性二萜类化合物,具有抗动脉粥样硬化、抗血栓形成、扩张血管及保护心肌等功效。近期的膜片钳全细胞式记录方法观察到其磺化后的水溶性钠盐丹参酮-A磺酸钠(TSN)对心肌的L-型钙通道具有阻滞作用,但其在整体条件下对心肌电生理作用的影响尚未见报道。2003～2004年,我们采用单相动作电位(MAP),观察了整体条件下TSN对家兔右室MAP和有效不应期(ERP)的影响,旨在探讨其在整体条件下的心脏电生理作用特点及潜在的抗心律失常机制。1材料与方法1.1实验动物及分组选择健康家…     

丹参酮ⅡA磺酸钠对家兔在体心脏单相动作电位影响的研究

丹参酮ⅡA（TashinoneⅡA）是从唇形科植物丹参的干燥根及根茎中提取出的脂溶性二萜类化合物,具有抗动脉粥样硬化、抗血栓形成、扩张血管及保护心肌等功效。近期的膜片钳全细胞式记录方法观察到其磺化后的水溶性钠盐丹参酮Ⅱ-A磺酸钠（TSN）对心肌的L-型钙通道具有阻滞作用,但其在整体条件下对心肌电生理作用的影响尚未见报道。2003～2004年,我们采用单相动作电位（MAP）,观察了整体条件下TSN对家兔右室MAP和有效不应期（ERP）的影响,旨在探讨其在整体条件下的心脏电生理作用特点及潜在的抗心律失常机制。     

粉防己碱抗氯化铯诱发家兔在体心脏早后除极及心律失常的作用

目的 :研究粉防己碱 (Tet)抗氯化铯 (CsCl)诱发触发活动及触发性心律失常作用。方法 :14只家兔分对照组和Tet组 ,Tet组给予Tet 0 5mg kg min共 10min ,对照组给予生理盐水 ,然后给予CsCl1 5mmol kg静注 ,给药前后记录心电图和右室心内膜MAP。结果 :Tet组和对照组均诱发EAD ,但Tet组EAD幅度低于对照组 ,室性心律失常发生率低于对照组。结论 :Tet有抗CsCl诱发EAD及室性心律失常作用。其机制可能是Tet抑制慢钙通道 ,减少内向电流。     

别隐品碱抗心律失常作用及其单相动作电位的作用

目的观察别隐品碱（ALL）的抗动物心律失常作用。方法以氯仿诱发小鼠室颤、以CaCl2-ACh混合液诱发小鼠心房纤颤、肾上腺素致豚鼠心律失常，以乌头碱诱发的豚鼠左室乳头肌收缩节律改变，选择大鼠结扎冠状动脉前降支，观察ALL抗心律失常的效应。记录豚鼠和大鼠心脏的动作电位和单相动作电位。结果ALL能明显降低氯仿诱发小鼠室颤率，应用30，100mg／kg的ALL后，CaCl2-ACh混合液诱发小鼠心房纤颤或扑动的发生率从100％降低到53．3％和33．3％。ALL使肾上腺素致豚鼠心律失常的持续时间降低，并对乌头碱诱发的大鼠心室乳头肌收缩节律失常有明显拮抗效应。ALL可明显延长其心脏的动作电位时程和不应期，这可能是其抗心律失常效应的电生理基础。结论ALL呈现出多种抗实验性心律失常的作用。     

四氢巴马汀对家犬在体心脏单相动作电位和有效不应期影响的研究

利用单相动作电位 (MAP)技术 ,研究在整体条件下四氢巴马汀 (THP)对家犬在体心脏MAP和有效不应期(ERP)的影响 ,从而探讨THP在整体条件下的抗心律失常机制。家犬 8只 ,体重 12 .5± 3.0 ( 10～ 15 )kg。同时记录家犬右室心尖部的MAP和体表Ⅱ导联心电图 (ECG) ,比较在窦性心律下用药前和用药后 10 ,2 0 ,30min的ERP、MAP复极 5 0 %时程 (MAPD5 0 )和复极 90 %时程 (MAPD90 )以及MAP振幅 (MAPA)的变化。结果 :用药后 10min ,各参数均无明显变化 (P >0 .0 5 ) ;用药 2 0min后 ,ERP、MAPD5 0 和MAPD90 与用药前相比 ,均明显延长 (分别为 139± 18msvs 12 4±18ms,12 6± 16msvs112± 15ms ,16 4± 2 5msvs 140± 16ms,P均 <0 .0 1) ,但用药前后ERP MAPD90 的比值无显著性变化 (P >0 .0 5 )。结论 :THP通过延长动作电位 2相和 3相时程 ,使ERP和MAPD90 平行延长 ,但不改变用药前后ERP MAPD90 比值 ,从而具有增加心肌电稳定性的作用 ,推测此是其具有抗室性心律失常的作用的可能机制     

蝙蝠葛碱及粉防己碱对电刺激时心脏去甲肾上腺素释放的影响

目的探讨碥蝠葛碱(Dau)和粉防己碱(Tet)对心肌去甲肾上腺素(NE)释放的影响.方法用高效液相色谱-电化学法测定豚鼠离体心灌注流出液NE的含量,将正常灌注下(S1)和不同条件灌注下(S2)两刺激进行前后对比.结果正常灌注及低氧高钾灌注,S2电刺激时心脏NE释放量与S1电刺激时无差别( P>0.05 );低氧灌注及低氧酸性灌注,S2电刺激时心脏NE释放量显著高于S1电刺激时( P< 0.01～0.001 );Dau及Tet可明显减少正常灌注、低氧灌注、低氧酸性灌注、及低氧高钾灌注S2电刺激时心脏NE释放 ( P<0.05～0.001 );Dau抑制正常灌注及低氧高钾灌注S2电刺激时心脏NE释放的作用弱于Tet,而抑制低氧灌注及低氧酸性灌注S2电刺激时心脏NE释放的作用强于Tet(P<0.05～0.01 ).结论 Dau及Tet可抑制电刺激时心肌NE释放,在不同条件下,二者作用程度不同.     

别隐品碱抗心律失常效应及其对动作电位的影响

目的研究别隐品碱(ALL)抗心律失常效应及其对心室肌动作电位的影响.方法选择大鼠和豚鼠以静脉给乌头碱、哇巴因和氯化钡造动物心律失常的模型,观察ALL对心律失常的效应,分离豚鼠乳头状肌观察ALL对动作电位的影响.结果ALL(30和100mg/kg)对乌头碱、哇巴因和氯化钡致动物实验性心律失常有良好的对抗作用,使各种试剂诱发的室早、室速、室颤及停搏的剂量增加.ALL可降低动作电位上升幅度(APA)和0相最大上升速率(Vmax).3.0～100.0 μmol/L的ALL以浓度依赖性方式使离体乳头状肌动作单位时程(APD)延长,其中30.0μmol/L的ALL使APD90延长67.5%.结论ALL具有抗实验性心律失常的效应,此效应可能与其影响心肌组织的电生理密切相关.     

Effects of antiarrhythmic drugs on the monophasic action potential of the canine isolated, blood-perfused ventricular septum preparation

Summary The present study was designed to combine the monophasic action potential (MAP) recording technique with a well-established canine isolated, bloodperfused ventricular septum preparation for examining, simultaneously, electrical and mechanical drug-induced changes. A MAP catheter was positioned onto the base of a papillary muscle for recording the local MAP, using a manual micromanipulator together with a commercially available catheter sheath to keep the optimal contact pressure against the ventricular wall. The catheter sheath was filled with saline to eliminate the background electrical noise. Tetrodotoxin, disopyramide, lidocaine, and verapamil were used to clarify the potential utility of the preparation. Tetrodotoxin and lidocaine shortened the MAP duration, while disopyramide prolonged it. Verapamil slightly shortened the MAP duration but not significantly. Each drug showed negative inotropic and coronary vasodilator effects. Sodium channel blockers slowed intraventricular conduction and decreased the maximum upstroke velocity of MAP, while verapamil showed no effects. These results suggest that utilization of the bloodperfused ventricular septum preparation together with MAP recording will become a valuable model for evaluating drugs with multiple sites of action on cardiac muscles.This study was supported in part by a Grant-in-Aid for Scientific Research (08770064) from the Japanese Ministry of Education, Science and Culture.     

急性缺血时犬3层心肌单向动作电位时程和有效不应期变化

目的:探讨急性缺血对犬在体3层心肌的电生理影响。方法:将12只犬随机分为急性缺血组(6只)和假手术组(6只)。应用单向动作电位(MAP)技术和特制的复合电极同步记录MAP和测定有效不应期(ERP),并分析跨室壁复极离散(TDR)和跨室壁不应期离散(TDE)。结果:在急性缺血组,MAP时程从[(201·67±21·42)ms缩短至(169·50±13·81)ms,P<0·05],而ERP不同程度地延长,且TDE增大。在假手术组,MAP时程和ERP没有明显变化。2组3层心肌之间MAP时程是一致的,不存在TDR。结论:急性缺血时MAP时程缩短,但3层心肌之间没有差别,而ERP延长伴随TDE增大。这可能在急性缺血时心律失常的发生中扮演重要角色。     

通过单相动作电位评价不同部位起搏时猪整体心脏复极离散变化

目的 通过对猪心脏不同部位起搏,观察不同激动顺序对整体心脏复极离散的影响.方法 10只健康猪,应用电解剖标测系统（Carto系统）,在右心房（RA）、右心室心尖部心内膜（RVEndo）及左心室后壁心外膜（ LVEpi）起搏,分别标测左心室（LV）及右心室（RV）心内膜单相动作电位（MAP）,测量不同部位起搏时的整体心室激动时间（AT）离散及整体心室复极结束时间（EOR）离散.结果 平均每个心室标测（ 121 ±35）个点,RA起搏时EOR为（63±12） ms,LVEpi起搏时EOR为（94±17） ms,RVEndo起搏时EOR为（72±18） ms; LVEpi起搏时EOR明显长于RA起搏时EOR（ P＜0.05）,RVEndo起搏与RA起搏EOR差异无统计学意义（P＞0.05）.结论 LVEpi起搏时整体心室肌复极离散较RA及RVEndo起搏时明显增加.     

In vitro validation of a new cardiac catheter technique for recording monophasic action potentials

Monophasic action potential (MAP) recording with non-suction, 'contact' electrode catheters has been shown possible and safe during clinical catheterization, but direct validation of this new technique is lacking. We therefore recorded these contact electrode MAPs simultaneously with transmembrane action potentials (TAPs) from closely adjacent sites in perfused and superfused rabbit septum preparations and performed a quantitative comparison between the two signals for duration and area at 30, 60 and 90% repolarization. To obtain a variety of action potential durations and configurations for the comparison, the rate and rhythm of stimulation and the extracellular calcium or potassium ion concentration were changed. With action potential duration at 90% repolarization made to vary from 150 to 513 ms, the mean absolute difference +/- SD between the simultaneous intra- and extracellular recordings was 5.4 +/- 11.3 ms and the linear correlation coefficient was r = 0.96 +/- 0.03. Similar agreement between the two types of recordings was found for measurements for area and at 60 and 30% repolarization levels. These data confirm that MAPs recorded with this clinically safe contact electrode technique can be used to measure accurately the repolarization time course of transmembrane action potentials.     

QT dispersion failed to estimate the global dispersion of ventricular repolarization measured using monophasic action potential mapping technique in swine and patients

The aim of this study was to evaluate whether the QT dispersion measured from 12-lead electrocardiogram (ECG) can estimate the global dispersion of ventricular repolarization (DVR) measured using a monophasic action potential (MAP) mapping technique. Monophasic action potentials were recorded from 75 +/- 12 left ventricular sites in 10 pigs and from 48 +/- 16 left or right ventricular sites in 15 patients using the CARTO mapping system. The maximum DVRs in both end-of-repolarization and MAP duration among all the mapped sites were calculated and termed as global DVR for each measurement. QT intervals, QT peak and QT end , were measured from the 12-lead ECG, and QT dispersions; namely the differences between the maximum and the minimum of the QT peak and QT end were calculated. We found that QT dispersions were significantly smaller than (P < .05) and poorly correlated with the global DVRs both in pigs and patients. Bland-Altman agreement analysis demonstrated a marked variation of the differences and an obvious lack of agreement between the results obtained using the ECG and the MAP methods. In our patients, the global DVR increased markedly during ventricular tachycardia as compared with that during sinus rhythm (P < .05), whereas there was no significant difference in QT dispersion between these 2 subgroups. In conclusion, QT dispersion on the surface ECG could not estimate the global DVR measured using the MAP mapping technique. These findings are not consistent with some previously reported observations, suggesting the need for reappraisal of the electrophysiological implications of QT dispersion.     

Dispersion of repolarization following double and triple programmed stimulation: A clinical study using the monophasic action potential recording technique

To study the dispersion of ventricular repolarization followingdouble and triple programmed stimulation and its correlationwith the inducibility of ventricular arrhythmias, monophasicaction potentials were simultaneously recorded from the rightventricular apex and outflow tract during programmed stimulationin 12 patients with ventricular arrhythmias and a normal QTinterval. The time difference between the ends of the two monophasicaction potentials were used as a measure of the dispersion ofventricular repolarization, which consists of the activationtime difference and the monophasic action potential durationdifference. During double and triple programmed stimulation, the dispersionof ventricular repolarization increased significantly with theshortening of the coupling interval but decreased slightly withthe shortening of the coupling interval but decreased slightlywith the shortening of the preceding interval. The inductionof the ventricular arrhythmias in these patients was invariablyassociated with a marked increase in the dispersion of ventricularrepolarization. The maximal dispersion of ventricular repolarizationwas significantly larger in the seven patients with polymorphicventricular tachycardia and/or ventricular flutter/fibrillationinduced than in the four patients with monomorphic ventriculartachycardia induced. Analysis of the two components of the dispersionof ventricular repolarization revealed that the increased dispersionof ventricular repolarization was mainly caused by an increasein the activation time difference in the monomorphic ventriculartachycardia subgroup, and by increases in both the activationtime difference and monophasic action potential duration differencein the polymorphic ventricular tachycardia/fibrillation subgroup. These findings suggest that increased dispersion of ventricularrepolarization is one of the underlying mechanisms accountingfor the myocardial vulnerability to ventricular arrhythmiasand that repolarization disturbance is important for the genesisof polymorphic ventricular tachycardia/fibrillation.     

门冬氨酸钾镁及其联合普罗帕酮对家兔心室肌电生理的影响

探讨门冬氨酸钾镁 (KMA)及其与普罗帕酮 (Pr)联合应用对心脏电生理的影响。将动物随机分组 ,分别静脉注射KMA、Pr以及KMA +Pr,采用心外膜单相动作电位 (MAP)记录技术于家兔左心室记录MAP。结果 :KMA、Pr、KMA +Pr各组均延长窦性心动周期 (SCL)、MAP复极达 5 0 %时程并增加心室有效不应期 (VERP) ;Pr、KMA +Pr还增加MAP复极达 90 %时程 (MAPD90 )及VERP/MAPD90 。较大剂量Pr有致心律失常作用 ,KMA与Pr联合使用心律失常发生率增加。结论 :KMA具有抗心律失常药物的电生理特性 ,单独应用推荐剂量的KMA是安全的 ;KMA与Pr联合应用的心脏电生理效应是两药各自作用程度的叠加。为避免致心律失常风险 ,KMA与Pr联合应用时应相应减小Pr剂量     

体表心电图、腔内单极电图与单相动作电位测定心室复极离散度相关分析

目的探讨心室复极离散度测定方法的可靠性.方法对19例无器质性心脏病者,应用左、右心室内膜单相动作电位(MAP)标测、腔内单极电图(UECG)和体表12导联同步心电图(ECG)3种方法研究心室复极离散度.结果UECG测值(UQ-Td,33±7ms)大于MAP测值(RTd,27±6ms,P＜0.01),而小于体表心电图测值(Q-Td,38±7m,P＜0.01),即Q-Td＞UQ-Td＞R-Td,但UQ-Td与R-Td、UQ-Td与Q-Td、R-Td与Q-Td均呈显著线性相关(r=0.75、0.87,0.78,P均＜0.01).结论体表心电图Q-Td可以代表心室复极离散.     

Recording monophasic action potentials using a platinum-electrode ablation catheter.

AIMS: The monophasic action potential (MAP) is conventionally recorded using Ag-AgCl electrodes which are not suitable for delivering radiofrequency currents. To be able to use the sharp MAP upstroke for identifying the local activation, as a step towards the development of a MAP-guided catheter ablation technique, the possibility of recording MAP via platinum electrodes of an ordinary ablation catheter was explored. METHODS AND RESULTS: One hundred and forty-two MAP recordings from the endocardium were obtained via an ablation catheter in 40 patients undergoing electrophysiological study/catheter ablation. During sinus rhythm and pacing, 90% of the ventricular and 100% of the atrial MAPs had stable baselines. The amplitudes were 13 +/- 4.2 mV for ventricular and 2.4 +/- 0.8 mV for atrial MAPs. During mapping and ablation, MAPs and uni- and bipolar electrograms were recorded simultaneously using the same tip electrode in eight patients. The MAPs provided more distinct local activation than the electrograms. During 17 MAP recordings, additional MAPs were recorded simultaneously using an Ag-AgCl electrode catheter in the immediate vicinity of the ablation catheter. The MAPs taken with the ablation catheter had characteristics consistent with those taken with the Ag-AgCl catheter. CONCLUSIONS: (1) Platinum electrodes can be used for timely recording of MAPs in patients. (2) It is feasible to record MAPs and deliver radiofrequency currents via the same platinum-tip electrode. These findings suggest that MAP-guided catheter ablation is technically possible.