Effect of WenxinKeli and quinidine tosuppress arrhythmogenesis in an experimental model of Brugada syndrome

Yoshino Minoura,MD,PhD,BrianK.Panama,PhD,VIadisIavV.Nesterenko,PhD,
Matthew Betzenhauser,PhD,HectorBarajas-Martinez,PhD,DanHu,MD,PhD,JoseM.DiDiego;MD;
Charles Antzelevitch,PhD,FHRS
(From the Masonic Medical Research Laboratory, Utica, New York.)

Background: Wenxin Keli(WK),a Chinese herb extract,is reported to be effective in the treatment of atrial and ventricular cardiac arrhythmias. Recent studies suggest that WK inhibits the transient potassium out ward current (Ito).

Objeot:  To examine the effectiveness of WK, alone and in combination with quinidine, to suppress arrhyth mogenesis in an experimental model of Brugada syndrome (BrS).

Methods:  Action potential and electroca rdiographic recordings were obtained from epicardia land endocardia Isites of coronary- perfused caninerightv entricular wedge preparations.The Ito agonist NS5806(10-15 NM) was used to pharmacologically mimic a genetic predisposition to BrS.

Results: The Ito agonist induced Phase2 reentry (P2R) in 139 preparations and polymorphic ventricular tachycardia (pVT) in 11/19 wedge preparations.WK(lOg/L)suppressed P2R and pVT in 100%(3/3) of preparations.A lower concentration of WK(5g/L) suppressed P2R in 60% (3/5) and pVT in 50%(2/4),but in combination with a low concentration of quinidine(5 NM), was 100% effective in suppressing P2R and pVT Quinidine alone suppressed P2R and pVT in 60%(3/5) and 50%(2/4), respectively, and incombination with WK(5g/L) suppressed P2R and pVT by 80% (4/5) and 75%(3/4), respectively. WK reduced Ito, the L-type calcium current,and contractility in single cardio myocytes,but dose-dependently increased contractility in intact wedge prepara一tions, an effect mimicked by tyramine. Conclusions Our data provide support. for the hypothesis that WK, particularly in combination with quinidine, effectively suppresses arrhythmogenesis in an experimental model of Br5 via
inhibition of Ito and indirect adrenergic sympathomimetic effects.

Keywords:  Transient outward potassium channel current; Positive inotropic effect; Cardiac arrhythmias; Suddendeath;wenxin keli

Wenxin Keli Suppresses Ventricular Triggered Arrhythmias via Selective Inhibition of Late Sodium Current

XIAOLIN XUE, M.D.,* DONGLIN GUQ M.D., PH.D.,t HONGMEI SUN, M.S.,*
DAN WANG, M.S.,* JIANA LI, M.S.,* TENGXIAN LIU, B.S.,t LIN YANG, M.D.,*
JUAN SHU, M.D., PH.D.,* and GAN-XIN YAN, M.D., PH.D.*,t,$
(*Department of Cardiology, the First Affiliated Hospital, Xi’ an Jiaotong University,Xi’ an, China;
tlankenau Institute for Medical Research and Main Line Health Heart Center, Wynnewood, Pennsylvania;
and #Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania〕

Background:  Wenxin Keli is a popular Chinese herb extract that approximately five million Asians are currently taking for the treatment of a variety of ventricular arrhythmias. However, its electrophysiological mechanisms remain poorly understood.

Methods and results: The concentration-dependent electrophysiological effects of Wenxin Keli were evaluated in the isolated rabbit left ventricular myocytes and wedge preparation. Wenxin Keli selectively inhibited late sodium current (INa) with an IC50 of 3.8 1 0.4 mg/mL, which was significantly lower than the IC50 of 10.6士0.9 mg/mL (n二6, P<0.05) for the fast INa. Wenxin Keli produced a small but statistically significant QT prolongation at 0.3 mg/mL, but shortened the QT and Tp-a interval at concentrations >_1 mg/mL. Wenxin Keli increased QRS duration by 10.1% from 34.8土1.0 ms to 38.3土1.1 ms (n二6, P< 0.01) at 3 mg/mL at a basic cycle length of 2,000 ms. However, its effect on the QRS duration exhibited weak use dependency, that is, QRS remained less changed at increased pacing rates than other classic sodium channel blockers, such as flecainide, quinidine, and lidocaine. On the other hand, Wenxin Keli at 1-3 mg/mL markedly reduced dofetilide-induced QT and Tp-a prolongation by attenuation of its reverse use-dependence and abolished dofetilide-induced early afterdepolarization (EAD) in four of four left ventricular wedge preparations, It also suppressed digoxin-induced delayed afterdepolarization (DAD) and ventricular tachycardias without changing the positive staircase pattern in contractility at 1-3 mg/mL in a separate experimental series (four of four). Conclusions: Wenxin Keli suppressed EADs, DADS, and triggered ventricular arrhythmia via selective inhibition of late INa. (PACE 2013; 36:732-740)

Keywords: Wenxin Keli, late sodium current, early afterdepolarization, delayed afterdepolarization,
triggered activities

Wenxin Keli attenuates ischemia一induced ventricular arrhythmias in rats

XI WANG, XIN WANG,YONGWEI GU, TENG WANG and CONGXIN HUANG
( Department of Cardiology Renmin Hospital of Wuhan University, Wuhan, PR. China

Abstract: Wenxin Keli is the first state一sanctioned traditional Chinese medicine (TCM)一based
antiarrhythmic drug. The present study aimed to examine whether long-term treatment with Wenxin
Keli reduces ischemia-induced ventricular arrhythmias in rats in vivo, and if so, which mechanisms are
involved. Male rats were treated with either saline (control group) or Wenxin Keli for 3 weeks and were
subjected to myocardial ischemia for 30 min with assessment of the resulting ventricular arrhythmias.
The L-type calcium current  and transient outward potassium current were measured by the patch clamp technique in normal rat cardiac ventricular myocytes. During the 30-min ischemia, Wenxin
Keli significantly reduced the incidence of ventricular fibrillation(VF) (P<0.05). The number of ventricular
tachycardia (VT)+VF episodes and the severity of arrhythmias were significantly reduced by Wenxin Keli
administration compared to the control group (P<0.05). In addition, Wenxin Keli inhibited I(cal) and I(to) in a
concentration-dependent manner. These results suggest that Tong-term treatment with Wenxin Keli may
attenuate ischemia-induced ventricular arrhythmias in rats and that I(cal) and I(to)  may be involved in this
attenuation.

Keywords: wenxin keli,ventricular arrhythmias, L-type calcium current, transient outward potassium current, patch clamp techniques, traditional Chinese medicines

wenxin keli and atrial fibrillation

Anthor:Masonic Medical Research Laboratory, Utica, New York 13501, USA

BACKGROUND:
Wenxin Keli is a Chinese herb extract reported to be of benefit in the treatment of cardiac arrhythmias, cardiac inflammation, and heart failure.

METHODS AND RESULTS:
We evaluated the electrophysiologic effects of Wenxin Keli in isolated canine arterially perfused right atrial preparations with a rim of right ventricular tissue (n = 11). Transmembrane action potentials and a pseudoelectrocardiogram were simultaneously recorded. Acetylcholine (1 μM) was used to induce atrial fibrillation (AF) and to test the anti-AF potential of Wenxin Keli (5 g/L). Wenxin Keli produced preferential abbreviation of action potential duration measured at 90% repolarization (APD(90)) in atria, but caused atrial-selective prolongation of the effective refractory period, due to the development of postrepolarization refractoriness. The maximum rate of rise of the action potential upstroke was preferentially reduced in atria. The diastolic threshold of excitation increased in both atria and ventricles, but much more in atria. The duration of the “P wave” (index of atrial conduction time) was prolonged to a much greater extent than the duration of the “QRS complex” (index of ventricular conduction time). Wenxin Keli significantly reduced I(Na) and shifted steady-state inactivation to more negative potentials in HEK293 cells stably expressing SCN5A. Wenxin Keli prevented the induction of persistent AF in 100% atria (6/6) and, in another experimental series, was found to terminate persistent acetylcholine-mediated AF in 100% of atria (3/3).

CONCLUSION:
Wenxin Keli produces atrial-selective depression of I(Na)-dependent parameters in canine isolated coronary-perfused preparations via a unique mechanism and is effective in suppressing AF and preventing its induction, with minimal effects on the ventricular electrophysiology.


Introduction
Effective and safe treatment of atrial fibrillation (AF) remains a major unmet medical need and the problem is growing as the prevalence of AF continues to increase with the aging of the population. AF is the most prevalent sustained clinical arrhythmia associated with increased morbidity and mortality. Its prevalence is 0.4-1% in the general population and greater than 8% in individuals >80 years of age. An estimated 2.5 million individuals in North America and 4.5 million in Europe are affected by AF. These numbers are projected to increase to up to15 million in North America alone by 2050, largely due to aging of the population.

Despite significant progress in radiofrequency and cryoablation therapy, antiarrhythmic drugs (AADs) remain first-line therapy for rhythm control of AF.1 However, the effectiveness and/or safety of agents available for the treatment of AF is less than optimal. Currently available pharmacologic strategies for the rhythm control of AF include: 1) sodium channel blockers, such as propafenone and flecainide; 2) potassium channel blockers (largely IKr), such as sotalol and dofetilide and 3) mixed ion channel blockers, such as amiodarone and dronedarone.

The development of safe and effective drugs for the management of AF remains a high priority.1 A major disadvantage of most of the drugs in current use is the risk of induction of ventricular arrhythmias. This risk can be reduced with the use of agents that selectively affect atrial electrophysiological parameters. Inhibition of the ultra-rapid delayed rectifier potassium current, IKur, present in atria, but not in the ventricles, is an example of an atrial-selective approach that has attracted much of the focus of the pharmaceutical industry in recent years.2 Recent studies have introduced the concept of atrial-selective block of peak sodium channel current as a novel approach for the management of AF, taking advantage of the electrophysiological distinctions between sodium channels of atrial and ventricular cells.3 A number of experimental studies have demonstrated the ability of sodium channel blockers like ranolazine, amiodarone and dronedarone to produce atrial-selective electrophysiological effects capable of effectively suppressing AF with minimal effects in the ventricle.3-10

Wenxin Keli is a Chinese herb extract reported to be of benefit in the treatment of cardiac arrhythmias, cardiac inflammation and heart failure. The extract is comprised of 5 components: Nardostachys chinensis batal extract (NcBe), Codonopsis, Notoginseng, Amber, and Rhizoma polygonati.

The present study was designed to evaluate the electrophysiologic effects and antiarrhythmic potential of Wenxin Keli in isolated canine arterially-perfused right atrial and ventricular preparations. We demonstrate an effect of Wenxin Keli to produce atrial-selective depression of INa-dependent parameters and to be effective in suppressing AF and preventing its induction, with minimal effects on ventricular electrophysiology.

Methods
Coronary-perfused canine right atrial preparations were used to study the effects of Wenxin Keli on electrophysiology of atrial and right ventricular parameters and on termination and induction of AF.

Effect of Wenxin Keli on acetylcholine (ACh)-induced AF

In the presence of 1 μM ACh, persistent AF is induced in 100% of coronary-perfused atrial preparations. We tested the ability of Wenxin Keli to terminate AF and prevent its re-induction in two separate series of experiments. In the first set, ACh was added to the perfusate 30-60 min after the start of Wenxin Keli (5 g/L) and followed by attempts to induce arrhythmias electrically (these experiments were performed in 6 preparations in which electrophysiological parameters were measured first). In the second set, Wenxin Keli was added to the perfusate during ACh-mediated persistent AF (on the 5-6th minutes after the start of the arrhythmia). In cases in which the drug successfully terminated AF, we attempted to re-induce AF with electrical stimulation.

Effect of Wenxin Keli on INa in HEK293 Cells

HEK 293 cells stably expressing WT-SCN5A and transiently transfected with WT-SCN1B using fugene were used to study the effect of Wenxin Keli on INa characteristics.

Statistics
Statistical analysis was performed using paired, unpaired t test as well as one way repeated measures or multiple comparison analysis of variance (ANOVA) followed by Bonferroni’s test, as appropriate. All data are expressed as mean±SD. p<0.05 will be considered significant.

Conclusions
Our data suggest that Wenxin Keli possesses potent anti-AF properties owing to its ability to depress sodium channel-dependent parameters. The atrial selectivity of this action of the drug likely contributes to its usefulness for safe and effective management of AF. The mechanism(s) of atrial selectivity of Wenxin Keli to inhibit INa appear to be unique and requires further study.