| Background The sick sinus syndrome(SSS)refers to a series of arrhythmias and clinical manifesta tions caused by activation and or conduction disorders caused by lesions of the sinoatrial n ode itself and its surrounding tissues.The occurrence of SSS is related to a variety of heart disease-related diseases.Untimely treatment can cause hemodynamic changes and cerebral blood supply insufficiency resulting in syncope,serious or even sudden cardiac death,seri ously threatening the life and safety of patients.Objective To explore the effects of SSS on histomorphology,automaticity and conduction function of sinoatrial node(SAN),and the analysis of therapeutic effect of Qiangxin Fumai granule.Methods A total of 36 rabbits were randomly divided into formaldehyde wet compress group(molding with formaldehyde wet compress),formaldehyde instillation group(molding with formaldehyde instillation)and sham operation group(non-molding),12 cases in each group.At 1 week after modeling,morphology and structure of SAN tissues were observed under light microscope.Before and at 1h after modeling,sinoatrial conduction time(SACT),sinu node recovery time(SNRT)and corrected sinus node recovery time(SNRTc)were measur ed by atrial pacing method.The relative expression levels of hyperpolarization-activated cy clic nucleotide-gated channel HCN1,HCN2,HCN3 and HCN4 mRNA in SAN tissues wer e detected by real-time fluorescence quantitative method.The level of HCN4 protein in SA N tissues was detected by Western Blot.A total of 60 rabbits were randomly divided into sham operation group,model group,low-dose,middle-dose and high-dose Qiangxin Fumai granulegroups and atropine group,10 cases in each group.Except sham operation group,SSS models were constructed in the o ther groups by formaldehyde wet compress method.After successful modeling,low-dose g roup(2.34g/kg),middle-dose group(4.68g/kg),high-dose group(9.36g/kg)and atropine gr oup(0.36g/kg)were given intragastric administration of the corresponding drugs,while sh am operationgroup and model group were given the same volume of normal saline.After a dministration,morphology and structure of SAN tissues were observed under light microsc ope.SACT,SNRT and SNRTc were measured byatrial pacing method.The severity of SA N function impairment in different groups was compared before and after administration.T he level of HCN4 protein in SAN tissues of each group was detected by Western Blot after administration.Results Compared with sham operation group,there were abnormal changes of SAN cells in formaldehyde wet compress group and formaldehyde instillation group.There was no significant difference in cells morphology between formaldehyde wet compress group and formaldehyde instillation group(P>0.05).Compared with sham operation group after modeling,SNRT,SNRTc and SACT were significantly higher in formaldehyde wet compress group and formaldehyde instillation group(P<0.05),which were higher in formaldehyde wet compress group than formaldehyde instillation group(P<0.05).HCN4 mRNA in formaldehyde wet compress group and formaldehyde instillation group was(0.86±0.09)and(0.63±0.07),lower than that in sham operation group [(1.02±0.01)],andwhich was lower in formaldehyde wet compress group than formaldehyde instillation group(P<0.05).The level of HCN4 protein in formaldehyde wet compress group and formaldehyde instillation group was lower than that in sham operation group,which was lower in formaldehyde wet compress group than formaldehyde instillation group(P<0.05).The morphology of SAN tissues could be improved in all administration groups.Compared with sham operation group,SNRT,SNRTc and SACT were longer in model group(P<0.05).Compared with model group,SNRT,SNRTc and SACT were shorterin low-dose group,middle-dose group,high-dose group and atropine group(P<0.05).The higher of the dose,the shorter the above time.Compared with shamoperation group before administration,scores of SAN function were higher in low-dose group,middle-dose group,high-dose group and atropine group(P<0.05).Compared with model group after administration,scores of SAN function were lower in low-dose group,middle-dose group,high-dose group and atropine group(P<0.05).With the dose increase of Qiangxin Fumai granule,scores of SAN function were decreased.Compared with sham operation group,expression of HCN4 protein was lower in model group(P<0.05).Compared with model group,expression of HCN4 protein was higher in low-dose group,middle-dose group,high-dose group and atropine group(P<0.05).The higher of the dose,the higher the expression of HCN4 protein.Conclusion 1.SAN injury induced by formaldehyde wet compressis a good animal model for SSS study,which can provide a good animal model and scientific theoretical basis to search for effective treatment drugs of SSS clinically.2.Qiangxin Fumai granules can effectively improve the morphology of SAN cells in SSS model rabbits,playa protective role on SAN,increase heart rate,and reduce arrhythmi a caused by SAN injury. |
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