Antiarrhythmic Mechanism Of Isoliensinine And Ginsenoside Rb1

Arrhythmia is the main complication of heart disease.Serious arrhythmias such as ventricular tachycardia and ventricular fibrillation can lead to sudden cardiac death.Therefore,arrhythmia is a public health problem endangering human life and health.There are two methods for the treatment of arrhythmia,one is surgical,such as implantation of pacemakers,implantable cardioverter defibrillators and catheterradiofrequency ablation;the other is anti-arrhythmic drug,such as amiodarone and verapamil.Although the effects of surgery treatment are obvious,there are various problems.Therefore,anti-arrhythmic drugs are still the most common strategy for the treatment of arrhythmias.At present,most anti-arrhythmic drugs are western medicines,but the side effects of western medicines are very serious.Therefore,many people try to develop anti-arrhythmic drugs from traditional Chinese herbal.Compared with western medicine,the development of Chinese herbal or its active monomers has many advantages.Since Chinese herbal has been used in China and even Asia for thousands of years,its clinical use,toxicity and side effects are known to us.The development of Chinese herbal has higher safety and lower cost compared with new western drugs.Zhigancao Decoction is a famous anti-arrhythmic prescription,on the basis of it,many antiarrhythmic Chinese medicines have been developed,such as Xinsuning.Xinsuning is consisted of eleven Chinese herbal including Glycyrrhiza uralensis Fisch,Coptis,Lotus Seed,Ginseng,Pinellia,Poria,Citrus aurantium,Dichroa febrifuga Lour,Sophora flavescens,Artemisia annua and Ophiopogon japonicus.Many active ingredients of these medicinal have been studied in anti-arrhythmia,but the anti-arrhythmic research of some active ingredients are not complete.Isoliensinine and ginsenoside Rb1 are extracted from lotus seed and ginseng,respectively.It is reported that they have a variety of pharmacological activities,especially for cardiovascular protection.Based on the above data,we speculated that isoliensinine and ginsenoside Rb1 have anti-arrhythmic potentials and their anti-arrhythmic mechanisms requires in-depth research.We used patch clamp technology to record the transient sodium current,late sodium current,L-type calcium current,potassium currents and action potentials of left ventricular myocytes and observed the effects of isoliensinine and ginsenoside Rb1 on these currents and action potentials.We also recorded calcium transients and observed the effect of ginsenoside Rb1 on it in ventricular myocytes.We established a variety of pathological models,such as hypoxia-reoxygenation,early afterdepolarization induced by anemone toxin II(ATX-II)and delayed afterdepolarization induced by extracellular high calcium.Under these pathological conditions,we observed how ginsenoside Rb1 affect intracellular calcium,how isoliensinine and ginsenoside Rb1 cured afterdepolarization which related to arrhythmia.Finally,we observed the effect of ginsenoside Rb1 on arrhythmia caused by ischemia-reperfusion injury.The experimental results show that isoliensinine inhibited the transient sodium current in a concentration-dependent manner.The half-maximal inhibitory concentration was 5.43 μmol/L.Isoliensinine(8 μmol/L)shifted the steady-state activation curve of transient sodium current to the right and shifted the steady-state inactivation curve to the left.At the same time,isoliensinine shifted the time-dependent recovery curve of the transient sodium current to the right.Isoliensinine also inhibited L-type calcium current in a concentration-dependent manner with the half-maximal inhibitory concentration of 1.18 μmol/L.Isoliensinine(2 μmol/L)shifted the steady-state inactivation curve of L-type calcium current to the left,but did not affect the steady-state activation curve and the time-dependent recovery curve.Isoliensinine(1,5,10 μmol/L)also inhibited the increased late sodium current induced by ATX-II,but had no effect on the inward rectifier potassium current and the delayed rectifier potassium current at the concentration of 20 μmol/L.Isoliensinine reduced the action potential amplitude and maximum upstroke velocity,shortened the action potential duration,but had no influence on the resting membrane potential.Isoliensinine can eliminate the early afterdepolarization induced by ATX-II and the delayed afterdepolarization induced by extracellular high calcium(3.6 mmol/L).Ginsenoside Rb1 inhibited the transient sodium current in a concentration-dependent manner.The half-maximal inhibitory concentration was 13.22 μmol/L.Ginsenoside Rb1(20 μmol/L)shifted the steady-state inactivation curve to the left,but did not affect the steady-state activation curve.Ginsenoside Rb1 also inhibited L-type calcium current in a concentration-dependent manner with the half-maximal inhibitory concentration of 41.89 μmol/L.Ginsenoside Rb1(80 μmol/L)shifted the steady-state inactivation curve of L-type calcium current to the left,but had no effect on the steady-state activation curve.Ginsenoside Rb1(40,80,160 μmol/L)did not affect the inward rectifier potassium current and the delayed rectifier potassium current.Ginsenoside Rb1 reduced the action potential amplitude and maximum upstroke velocity,shortened the action potential duration,but had no influence on the resting membrane potential.Ginsenoside Rb1 not only reduced the intracellular calcium concentration,inhibited the occurrence of calcium overload caused by hypoxia-reoxygenation,but also eliminated the delayed afterdepolarization induced by extracellular high calcium(3.6mmol/L).Ginsenoside Rb1(40 μmol/L)reduced the number of ventricular premature beats and delayed the onset time of ventricular premature beats which caused by ischemia-reperfusion injury.Ginsenoside Rb1 also decreased the incidence of ventricular tachycardia.In summary,isoliensinine exerts anti-arrhythmic effects by inhibiting transient sodium current,L-type calcium current and late sodium current,eliminating the occurrence of early and delayed afterdepolarization;Ginsenoside Rb1 exerts anti-arrhythmic effects by inhibiting transient sodium current,L-type calcium current,reduce intracellular calcium concentrationl and inhibit calcium overload.