| Objectives:In this study,spinal cord stimulation was used to intervene in the Beagle atrial fibrillation model to investigate the effect and the behavior of the dogs.To observe the effect of expression of HSP70 in atrial myocardium in spinal cord stimulation intervention for atrial fibrillation.Method:1?Select 18 adult beagle,male and female informal,and randomly divide into blank control group(Ctrl group,6:without atrial fibrillation model,without spinal cord stimulation);atrial fibrillation model group(AF group,6:only with atrial fibrillation,without the spinal cord stimulation);group(SCS group,6:atrial fibrillation model in the spinal cord stimulation).(1)AF group and SCS group,implant single-chamber pacemaker and active fixed electrode,to establish right atrial pacing system.Continuously increasing frequency and over-speed pacing atrial to build atrial fibrillation dog model.Record body lead electrocardiogram(ECG)regularly.Subcutaneously implanted Reveal LINQ tracker to monitor arrhythmia events such as atrial fibrillation.(2)In the SCS group,implant the spinal cord thorax segmental electrode to establish the spinal cord electrical stimulation system.High-frequency,low-energy spinal cord stimulation for 12 weeks in model dogs.During the period of spinal cord stimulation,observe closely the behavior of the dogs and use of Reveal LINQ tracker Monitoring the AF.Using ultrasonic cardiogram to measure left atrium area to assess effects of treatment.2.Executed experimental dogs,collect left atrium tissue.Based on the previous studies to screen differential genes by transcriptome sequencing,using qRT-PCR test the expression of HSP70 in atrial myocardium,and explored the mechanism of related signaling pathways preliminarily.Result:1?(1)3 dogs died during the process of establishing atrial fibrillation model in AF group and SCS group,which were considered to be associated with malignant arrhythmias.The success rate of model was 75%,and the time to establish a successful atrialfibrillation was 9.44±0.88 weeks;When the atrial fibrillation model is successful,atrial stimulation frequency of high frequency atrial fibrillation model pacemaker is 582.22±20.48 times/min.Atrial fibrillation events are self-induced without procedural stimulation.(2)Both the SCS group and the AF group monitor the atrial fibrillation load successfully using Reveal LINQ.the atrial fibrillation load of SCS group was significantly lower than that in AF group(7.26±1.38 vs.46.60±3.25,P<0.001).(3)Using Ultrasonic Cardiogram to measure left atrium area,the area of left atrium in AF group was significantly enlarged than Ctrl group(8.38±0.59 cm2 vs.3.55±0.15cm2,P<0.05);the area of leftatrium in SCS group was significantly smallerthan AF group(5.00±0.91 cm2 vs.8.38±0.59cm2,P<0.05);the area of left atrium in SCS group was enlarged than Ctrl group(5.00±0.91cm2 vs.3.55±0.15cm2,p<0.05).(4)The alternating current frequency of SCS was adjusted to 50 Hz,the pulse width was 0.21 ms,the output voltage started from 0.1 V,and increased gradually by 0.05 V.Each time raising the output voltage for 5 hours,the proximal muscles of the forelimb of the dog can be contracted and finely tremor.The tremor can be felt with the hand,the muscles are stiff,and the body is laterally bent with varying degrees;The dog started to scream at raising the stimulation preliminarily.After a few minutes,recovering calmly,activity decreased,stretching tongue,salivating,and urination increasing.The above performance was obvious within the first 2 hours of the stimulation,and then the experimental dog gradually appeared as usual,the muscle tremor was weakened,and the degree of lateral curvature was reduced.Experimental dogs have no abnormal performance without SCS.After implantation of SCS,there were 2 dogs with swelling of the capsular,and 1 dog showed capsular rupture and returned to normal after treatment.2.(1)Detection the expression of HSP70 gene by qRT-PCR,the results show that,compared with the Ctrl group,the expression of HSP70 in the AF group was significantly down-regulated(P<0.01);compared with the AF group,the expression of HSP70 in the SCS group was significantly up-regulated(P<0.05).Detection of HSP70 protein expression by western blot,the results show that,the expression level of HSP70 in the AF group was significantly lower than that in the Ctrl group and the SCS group(P<0.001).The expression level of SCS group was significantly higher than that of AF group(P<0.001).Gene expression of HSP70 is consistent with protein expression.(2)Forecasting HSP70 gene-related signaling pathways according to KEGG pathway function analysis,it was found that the SCS group mainly activated the MAPK signaling pathway compared with the Ctrl group.It is speculated that the mechanism of SCS treating AF may be related to the up-regulation of HSP70 expression in MAPK signaling pathway.Conclusion:1.Continuously over-speed pacing right atrial to build dog atrial fibrillation model with high success rate and stable model.2.SCS can reduce the load of atrial fibrillation and reverse atrial remodeling in atrial fibrillation dogs.3.Although SCS has an effect on the behavior of experimental dogs,it is safe and feasible.4.1t may be one of the key mechanisms for SCS treatment of AF that promoting up-regulation of HSP70 expression in MAPK signaling pathway in the atrial myocardium. |
PDF Full Text Request