风湿性瓣膜病心房颤动患者右心房超极化激活电流密度及其通道表达的变化

Atrial funny current（ If） density and hyperpolarizafion-activated cyclic nucleotide-gated channel expression in atrial fibrillation patients with rheumatic heart disease

目的比较风湿性心脏瓣膜病心房颤动患者和窦性心律患者右心房单个心肌细胞超极化激活电流（If）密度及超极化激活的环核苷酸门控（HCN）通道表达的变化。方法应用全细胞膜片钳技术记录25例房颤患者和16例窦性心律患者右心耳单个心房肌细胞If的变化，并用Westernblot法检测两组患者右心耳组织HCN通道的表达水平。结果相同激活电位时，房颤组患者右心耳单个心房肌细胞If电流密度明显大于窦性心律组，且随电位增加激活更快，尤其在-70mV时，房颤组和窦性心律组If电流密度分别为（一43．74±2．87）和（-26．81±1．41）pA／pF，此时两组比较差异有统计学意义（P〈0．01）。房颤组HCN2、HCN4通道表达水平分别为0．44±0．20和0．53±0．20，与窦性心律组的0．23±0．13和0．36±0．18比较均明显增高（P〈0．01）。结论心房组织If电流密度增大及HCN通道表达上调参与了心房电重构，在房颤发生和维持中发挥作用。

Objective To study the changes of both litany current （If） density and expression lev- els of hyperpolarization-activated cyclic nucleotide-gated （HCN） channel in muscles of right atrium in rheu- matic heart disease patients with atrial fibrillation （AF） in comparison to those in normal sinus rhythm （SR）. Methods It density was measured by using whale-cell patch clamp technique in single myocyte isola- ted by an enzymatic dissociation method from right atrial appendages in patients with AF （n = 25） and those with SR （n = 16）. The expression levels of HCN channel were also determined in right atrial appendages from patients with AF and those with SR by Western boltting. Results If density in single myocyte was sig- nificantly increased at same test potential in AF compared to that in SR. And the difference reached peak with the test potential of -70 mV [ （ -43.74 ± 2. 87） vs. （ - 26. 81 ± 1.41 ） pA/pF,P 〈 0. 01 ]. The ex- pression levels of HCN2 and HCN4 channels were also significantly higher in AF than those of SR [ （0. 44 ± 0. 20） vs. （0. 23 ±0. 13） and （0. 53 ±0. 20） vs. （0. 36 ±0. 18） ,P 〈0. 01 ]. Conclusion The data suggest that the increase of If density and HCN channel up-regulation might contribute to the atrial electrical remode- ling which participates in the progress of AF development in rheumatic heart disease.