Blocking TRPV4 Inhibits Inflammation And Reduces Ventricular Arrhythmias After Ischemia-reperfusion

Objective:By establishing stable ischemia reperfusion(MIRI)model and using right ventricular S1S2 electrical stimulation to induce the occurrence of ventricular arrhythmia after MIRI,and to explore the effect of TRPV4 channel on the occurrence of ventricular arrhythmia after MIRI and its possible mechanism.Methods:In this study,C57BL/6 mice were divided into 7 groups:1)Sham group;2)MIRI group(WT+I/R group);3)TRPV4 blocker GSK2193874 group(GSK2193874+I/R group);4)Vehicle1 group(given equal amount of saline without GSK2193874);5)TRPV4 agonist GSK1016790A group(GSK1016790A+I/R group);6)Vehicle2 group(given equal amount of saline without GSK1016790A);7)TRPV4-/-group(TRPV4-/-+I/R group).By ligating the left anterior descending coronary artery(LAD)for 30 min and then the reperfusion of LAD for 24 h to preparate MIRI model,making use of the TRPV4-/-mice,TRPV4 channel blocker GSK2193874 and TRPV4 agonists GSK1016790A to change the activity of TRPV4 channels,and then meansuring the myocardial infarction area,cardiac function,serum myocardial enzyme LDH of MIRI rat,to evaluate the stability of the model of MIRI and detect the effects of TRPV4 channels on myocardial injury in MIRI mice.The right ventricular S1S2 electrical stimulation was used to induce the occurrence of ventricular arrhythmia after MIRI,and the expression of myeloperoxidase(MPO)was detected by immunohistochemical method and the expression of inflammatory factors was detected by RT-PCR.Results:(1)compared with Sham group,after mice experienced 30 min of ischemia and 24 h of reperfusion,myocardial infarction area increased significantly,left ventricular ejection fraction(EF)and left ventricular short axis shortening rate(FS)decreased,and serum LDH expression increased.Compared with Vehicle1 group,the use of TRPV4 blocker GSK2193874 significantly reduced the myocardial infarction area,increased EF and FS values,and decreased serum LDH expression in MIRI mice.Compared with Vehicle2 group,TRPV4 agonist GSK1016790A increased the myocardial infarction area,decreased EF and FS values,and increased serum LDH expression in MIRI mice.Compared with WT+I/R group,TRPV4-/-+I/R group had significantly less the myocardial infarction area,higher EF and FS values,and less LDH expression in serum.(2)Compared with the Sham group,the incidence of ventricular tachycardia(VT)was increased after right ventricular S1S2 electrical stimulation after 24 hour’s reperfusion in MIRI group(I/R group),and the duration of VT was significantly prolonged.Compared with Vehicle1 group,TRPV4 blocker GSK2193874 significantly reduced the occurrence and duration of VT after ischemia-reperfusion.Compared with the WT+I/R group,the occurrence and duration of VT in the TRPV4-/-+I/R group were significantly decreased.(3)Compared with Sham group,MPO expression in myocardial tissue of WT+I/R group was increased.The use of TRPV4 blocker GSK2193874 can reduce the expression of MPO in myocardial tissue after ischemia-reperfusion,while the use of TRPV4 agonist GSK1016790A can increase the expression of MPO in myocardial tissue.(4)At 6 hours post reperfusion,compared with Sham group,CXCL-1,CXCL-2,CXCL-3,CXCL-12,ICAM-1,MCP-1,IL-6,IL-1β,MIP-2 expression was increased in WT+I/R group,while CXCL-5,CXCL-7 and TNF-α expression were not significantly different from Sham group.Compared with Vehicle1 group,TRPV4 blocker GSK2193874 can effectively reduce the expression of CXCL-2,IL-6 and MIP-2 in the myocardial tissue,but there was no significant difference in the rest.Conclusion:(1)TRPV4 channel protein is involved in the occurrence and development of MIRI.TRPV4 blocker GSK2193874 can significantly reduce the myocardial injury after MIRI,while TRPV4 agonist GSK1016790A can aggravate the myocardial injury after MIRI.(2)The TRPV4 channel is involved in the occurrence and development of ventricular arrhythmia after MIRI.The use of TRPV4 blocker GSK2193874 can effectively reduce the occurrence and duration of VT.(3)The change of TRPV4 channel affected the expression of MPO in the myocardial tissue after MIRI.GSK2193874 could effectively reduce the expression of MPO in the myocardial tissue after MIRI,while the expression of MPO in the myocardial tissue increased after using GSK1016790A.(4)TRPV4 blocker GSK2193874 could effectively reduce the expression of CXCL-2,IL-6 and MIP-2 in the myocardial tissue after MIRI.