The Relationship Between Expression Of Interleukin-17and Ventricular Arrhythmia In Post-myocardial Infarction Rats

Objective To study the Expression of Interleukin-17of myocardium after myocardial infarction in the rats.Methods Liquid nitrogen freezing method was used to establish rat MI model.66rats with modeling successful were randomly divided into six groups according to different observation times:1d,3d,1w,2w,4w,8w groups. And8rats were selected as control. The expression of interleukin-17was examined by enzyme linked immunosorbent assay, laser confocal scanning microscope and Western blot.Results Modeling success rate was73%. With the development of myocardial infarction, interleukin-17was abundantly expressed in myocardial and gradually increased over time, and interleukin-17in the28days group was expressed the most significant.Conclusion Interleukin-17as a potent pro-inflammatory factor can strongly express in rat myocardium after MI, which may be related to the incidence of ventricular remodeling and arrhythmia.Part Two Effects of IL-17expression on ventricular arrhythmias in Post-Myocardial infarction Rats Objective To investigate the effect of IL-17expression on ventricular arrhythmias in Post-Myocardial infarction Rats.Methods Liquid nitrogen cryoinjury method was used to establish myocardial infarction model. The MI model were randomly divided into3groups, MI control group, IgG group and Antibody group. Then each group was randomly divided into3sub-groups:2week,4week and8-week group. Sham group(S group) was established. The first day after operation, PBS solution were intraperitoneally injected to sham group and MI control group, mouse isotype IgG1and PBS to IgG group, monoclonal human IL-17antibody and PBS to Antibody group,5times every two days. Programmed electrical stimulation was used to induce ventricular arrhythmia (ventricular tachycardia and ventricular fibrillation) in the four groups.The evoked electrocardiograms and evoked rates were recorded. The protein expression of Interleukin-17was examined by Western blot and LSCM.Result Compared to sham group, expression of IL-17in myocardium in MI control group, IgG group and Antibody group increased obviously (P<0.05) at2weeks,4weeks and8weeks after operation, also increased the evoked rates of ventricular arrhythmia(P<0.05); Compared to MI control group and IgG group, expression of IL-17in Antibody group was lower(P<0.05),and the evoked rates decreased(P<0.05) too. While, obvious differences were not found between MI control group and IgG group. Statistic analysis showed that there was a positive linear correlation between expression of IL-17and the evoked rate(r=+0.88, P<0.05). Compared to2weeks,the evoked rates of4weeks and8weeks in MI control group, IgG group and Antibody group did not change (P>0.05)Conclusion IL-17expression was significantly increased after MI. There is relationship between a large number of IL-17expression and ventricular arrhythmias in Post-Myocardial infarction Rats. High expression of IL-17may induce or promote the formation of the reentrant circuit of ventricular arrhythmias in Post-Myocardial infarction Rats. Objective To study the effects of Interleukin-17(IL-17)on ventricular arrhythmias in vitro rat heart and to study the mechanism of ventricular arrhythmias.Methods The isolated rat hearts were perfused with Krebs-Henseleit (K-H) solution via aorta at37℃. Different concentrations of IL-17were added to observe the arrhythmia.Results Different concentrations of IL-17could cause ventricular arrhythmias. The frequency of ventricular arrhythmias was interrelated with the concentrations of IL-17(P<0.05). Using IL-17antibody treatment, ventricular arrhythmias by the same concentration the IL-17was significantly reduced compared with the previous (P<0.05).The evoked rates of ventricular arrhythmias decreased(P<0.05) too.Conclusion IL-17in vitro can lead to ventricular arrhythmias. Objective To investigate the effects of Interleukin-17(IL-17) on the transient outward potassium currents (Ito) in isolated cardiomyocytes of rat.Methods The single ventricular myocytes of rats were obtained by enzymatic dissociation. Ito was recorded by using whole cell patch clamp technique.Results The inhibitory effect of IL-17on Ito current density increased with the concentration of IL-17increasing (≥37.5ng/L). The Inhibitory rate of37.5,75,150,300,600ng/L of IL-17on Ito current density were12.7±3.4%(P<0.05vs control),20.3±5.5%(P<0.05),27.1±6.0%(P<0.05),35.7±7.1%(P<0.05),47.2±9.3%(P<0.01), respectively.Conclusions IL-17inhibits Ito current density in a concentration-dependent manner, which may be related to the incidence of ventricular arrhythmias.