Electrophysiological Mechanism Of Salidroside On Myocardial Ischemia-reperfusion Arrhythmia In Rats

BackgroundIschemicheartdisease（IHD）is currently one of the important causes of human death in the world.The reperfusionarrhythmia（RA）occurring after myocardial ischemia and reperfusion is an important factor threatening the lives of patients.The prevention of myocardial ischemia-reperfusion arrhythmia is particularly important in the treatment of acute coronary syndrome（ACS）.Salidroside（SAL）has the effects of anti-inflammatory,anti-oxidation and repairing myocardial cells.It is reported that the drug may have the effect of inhibiting arrhythmia,but the specific mechanism is not clear.ObjectiveFrom the perspective of cardiac electrophysiology,this study studied the mechanism of salidroside on myocardial ischemia-reperfusion arrhythmias in isolated rat hearts,and further provided a new strategy for the treatment of myocardial ischemia-reperfusion arrhythmias in clinical patients.Method1.Dose effect experiment: 280 ± 20 g male SD rat hearts were placed on Langendorff perfusion system,Krebs Henseleit（K—H）solution was given for circulation,and electrocardiograms（ECG）electrodes,stimulation electrodes and matrix multi-channel electrophysiological mapping electrodes were attached.Using multi-channel electrophysiological mapping system（Mapping Lab）and emapscope software to analyze Sal（1 μg/ml、5 μg/ml、25 μg/ml、50 μg/ml、75 μg/ml）effective refractory period（ERP）before and after intervention in isolated heart,further analyze cardiac conduction velocity and time,and determine salidroside concentration in ischemia-reperfusion experiment;2.Ischemia reperfusion experiment: SD rats were randomly divided into Sal group and model group.After taking out the heart,they were placed on the perfusion system to give K-H solution circulation,and attached with ECG electrode,stimulation electrode and matrix multi-channel electrophysiological mapping electrode.Sal group was given Sal 5μg/ml before ischemia.After 10 minutes of intervention,the anterior descending branch was ligated and reperfusion was given for 15 minutes after 15 minutes of ischemia.ECG was recorded at 0 minutes,1 minutes,2 minutes,3 minutes,5 minutes,10 minutes and 15 minutes of ischemia and reperfusion respectively.The incidence of ventricular fibrillation（VF）,ST elevation,cardiac conduction velocity,conduction time and conduction dispersion were observed by using mappinglab and emapscope software.In case of ventricular fibrillation after reperfusion,the detection was stopped.The model group performed the same operation without Sal intervention;3.Patch clamp experiment: 1550 A digital to analog converter and pclamp10.6acquisition and analysis software are used.The borosilicate hard glass electrode is drawn with a drawing instrument.After filling the liquid in the electrode,the electrode resistance is between 2—5MΩ.The pretreated Chinese hamster ovary（CHO）cells stably expressing Nav1.5 channel protein were placed in a bath,and 100μL or so cell suspension was inoculated on cell climbing tablets,and salidroside 50μg/m L was applied after 2 hours of adherence acts on cells.Select an independent single cell and adjust it to a clear field of vision.Fix the drawn microelectrode on the multiclamp700 a amplifier probe.Use the microelectrode manipulator to inject the electrode into the liquid.After the electrode contacts the cells,give negative pressure.Use 6KHz filtering to record the electrophysiology.The cell clamp was placed at-120 mv,depolarized from-120 mv to-15 mv,and the duration was 100 ms.The clamp voltage was adjusted to inactivate the channel current by about 20%.Each sweep was 5S.The changes of Nav1.5 channel current before and after salidroside treated CHO were recorded.Result1.Dose effect experiment: according to the results of electrical mapping,with the increase of SAL concentration,the heart conduction time becomes shorter and the conduction velocity accelerates.From administration to 5 μg/ml,the average conduction velocity of left ventricle was the fastest,which was significantly different from that before administration（p<0.05）;2.Ischemia reperfusion experiment:（1）Compared with the model group,the incidence of VF in SAL group decreased;（2）ECG showed that ST segment elevation in SAL group was lower than that in model group;（3）The results showed that under 6Hz stimulation and spontaneous rhythm,the conduction velocity of the model group and sal group after left ventricular ischemia was significantly slower than that before ischemia,and the conduction dispersion of the model group was significantly higher than that before ischemia（p<0.001）;Compared with the model group,the conduction velocity of SAL group increased significantly（p<0.05）and the conduction dispersion decreased（p<0.01,p<0.001）before and after ischemia;Before and after ligation of the right ventricle under6 Hz stimulation,the conduction velocity of SAL group was significantly faster than that of the model group,and there was no significant difference in spontaneous rhythm and conduction dispersion;3.Cell experiment: patch clamp results showed that salidroside of 50μg/ml had no inhibitory effect on the peak Na current and I—V（voltage current relationship）curve on Nav1.5 stable cells,but it could shift the activation curve of Na current to the left and make the channel easier to activate.ConclusionSalidroside can accelerate the conduction velocity of myocardial ischemic area,reduce the conduction dispersion,protect myocardium and reduce the occurrence of myocardial ischemia-reperfusion arrhythmia.The mechanism is related to salidroside moving the activation curve of Nav1.5 channel to the left,reducing the excitation threshold and making myocardial cells more excited.