| AIM: To study the relationship between the activation of PI3K/AKT signaling pathway and the expression of Cx43,Kir2.1 in ischemic myocardial cells of rats.To investigate the role of PI3K/Akt signaling pathway in the regulation of ischemic arrhythmia mediated by microRNA-1 in ischemic cardiomyocytes,and to find potential targets and possible measures for prevention and treatment of ischemic arrhythmia.Contents and Methods: Eighteen SD rats were randomly divided into three groups:sham group,LY294002 inhibitor intervention group(LY group)and myocardial infarction/solvent group(DMSO group),with 6 rats in each group.(1)Establishment of rat model of myocardial infarction.Establishment of rat model of myocardial infarction by ligation of LAD coronary artery.Monitoring ECG activity and TTC staining were used to detect infarct area.(2)The supernatant of ischemic myocardial cells in the marginal zone of myocardial infarction was prepared.The expression levels of key proteins AKT,p-AKT,GSK-3?,p-GSK-3?,CX43 and Kir2.1 were detected by Western blot.(3)The expression levels of GJA1/Connexi43 and KCNJ2/Kir2.1 related genes in myocardial cells were detected by real timePCR.(4)Statistical analysis.The measurement data were expressed as mean ±standard deviation(x±s).Normality test and homogeneity test of variance,two-sample t test and Satterthwait approximate t test were carried out.The counting data were tested with four-table data.The difference was statistically significant with P < 0.05.Results: In DMSO group and LY group,one rat died during the experiment,and the mortality rate was 16.7%.With the lapse of ligation time of coronary LAD,the level of ST-T wave continued to rise with the lapse of time,and remained relatively constant after the peak of ischemia for about 20 minutes.Occasional ventricular premature was observed in Sham group,and no ventricular tachycardia was found.Compared with Sham group,the incidence of premature ventricular tachycardia and ventricular tachycardia was higher in DMSO group and LY group(p < 0.05).Compared with DMSO group,LY group had higher incidence of premature ventricular tachycardia and ventricular tachycardia(28 +3.12 vs 36 +5.23;5.1 +1.52 vs 8.2 +3.42,P < 0.05).The infarct size in DMSO group was smaller than that in LY group(31.7±4.8% vs 36.8±6.94%,P < 0.05).Compared with the Sham group,the expression levels of p-Akt,p-GSK-3?,Cx43 and Kir2.1 in the DMSO group were significantly lower(2.02±0.30vs1.60±0.16;2.21±0.17vs1.82±0.15;1.79±0.12 vs 1,42±0.09;2.08±0.25vs1.68±0.14,P < 0.05).There was no significant difference in the expression levels of AKT and GSK-3? between the two groups(0.90±0.08 vs 0.80±0.06;0.97±0.07 vs 0.90±0.08),P > 0.1).Compared with the Sham group,the expression levels of p-Akt,p-GSK-3?,Cx43 and Kir2.1 in PI3K/Akt signaling pathway inhibitor LY294002 pretreatment group(LY group)decreased further,while the expression levels of non-phosphorylated AKT and GSK-3? also decreased(0.60±0.06vs0.97±0.07;0.42±0.03vs0.75±0.05,P<0.01).The expression levels of GJA1/Connexi43 and KCNJ2/Kir2.1 related genes in DMSO group were not significantly different from those in Sham group(3.28±0.08vs3.35±0.21;2.81±0.15vs2.9±0.4,P > 0.5).In LY group,the expression levels of GJA1/Connexi43 and KCNJ2/Kir2.1 related genes were significantly lower than those in Sham group(1.71±0.06vs3.35±0.21;0.51±0.04vs2.9±0.4,P < 0.01).CONCLUSION: PI3k/AKT/GSK-3? signaling pathway in ischemic rat cardiomyocytes is relatively inhibited,which shows that the expression and phosphorylation levels of key proteins AKT,GSK-3? are decreased,accompanied by the decrease of Cx43 and Kir2.1 protein expression levels,but the levels of GJA1/Cx43 and KCNJ2/Kir2.1 related genes are not decreased.In addition,inhibition of PI3k/Akt signaling pathway aggravates ischemic myocardial injury and enlarges the scope of myocardial infarction and increases the incidence of ischemic arrhythmia in rat models of myocardial infarction. |
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