Expression Level Of Hyperpolarization-activated Cyclic Nucleotide Cardiac Death In Sinoatrial Node

Objective Through detecting the expression level of hyperpolarization-activated cyclic nucleotide-gated channel 2(HCN2)and ankyrin-B(ANK2)in sinoatrial node in patients with Sudden cardiac death(SCD)and non SCD,to investigate the expression changes of HCN2 protein and ANK2 protein in SCD patients of sinus node and its significance.Methods 27 sudden cardiac death cases were collected as the experimental group from September 2015 to March 2016 from the department of pathology,Qingdao Municipal hospital,of which,23 cases were diagnosed coronary heart disease,4 cases vital myocarditis.13 cases died for traffic accident or trauma were obtained as control group.Cardiac sinoatrial node tissues were accurately cutted.After paraffin embedded,partial sections were dyed with H&E staining,partial sections were immunostained with HCN2 and ANK2 antibodies,t test and Pearson correlation coefficient were performed for statistical analysis.Result1.Pathological observation of sinus node:Several pathological changes of sinus node were found in both SCD group and non SCD group,including fat infiltration,fibrosis,arterystenosis and chronic inflammation,the difference was statistically significant(p=0.011<0.01).2.Expression of HCN2 in sinoatrial node:HCN2 protein was expressed in the P cells and T cells of sinoatrial node tissues,HCN2 showed paranuclear dot-like staining in SCD group and non SCD group.The HCN2 expression in the sinoatrial node of SCD group was dark brown or dark yellow;While light yellow or negative in non SCD group.HCN2 protein expression in sinoatrial node tissues of SCD group was higher than that in non SCD group,the difference was statistically significant(p<0.01).3.Expression of ANK2 in sinoatrial node:The localization of ANK2 protein in the sinoatrial node was cytoplasm in P cells and T cells.In SCD group,the pattern expression of ANK2 was sparse and minor,while in non SCD group was dark yellow.The expression of ANK2 protein in SCD group was significantly lower than that in control group,the difference was statistically significant(p<0.01).4.Correlation analysis of HCN2 and ANK2 expression:Correlation analysis of HCN2 and ANK2 expression was analyzed by Pearson rank.The results showed there was no significant correlation between the expression of ANK2 and HCN2 protein(r=-0.453,p=0.12>0.05).Conclusion Pathological changes were investigated in SCD and non SCD group.The downregulation of HCN2 and upregulation of ANK2 protein expression in sinoatrial node seem to play an important role in sudden cardiac death.Significance In this study,we investigate the expression level of HCN2 protein and ANK2 proteinin in sinoatrial node in patients with SCD,and overcame the limitations of previous animal models.The experimental results show that abnormal protein expression level of HCN2 and ANK2 may be associated with the occurrence of SCD,providing an important reference value for the diagnosis of unexplained SCD,to help patients looking for the cause of death,but also to help early prevention and treatment of sudden cardiac death.