Sodium current kinetics of transitional myocytes in Koch triangle of rabbit hearts  

作　　者：REN Fu-xian NIU Xiao-lin OU Yan XIE Song-mei LING Feng-dong ZHOU Shi-sheng LI Ya-jie 

机构地区：[1]Department of Cardiology, Second Hospital, Xi'an Jiaotong University, Xi'an, Shaanxi 710004, China [2]Key Laboratory of Environment and Genes Related to Diseases, Ministry of Education, Xi'an, Shaanxi 710061, China [3]Department of Anatomy, Xi'an Jiaotong University School of Medicine, Xi'an, Shaanxi 710061, China [4]Institute of Basic Medical Science, Dalian University School of Medicine, Dalian, Liaoning 116622, China

出　　处：《Chinese Medical Journal》2008年第21期2185-2191,共7页中华医学杂志（英文版）

基　　金：This study was supported by the National Natural Science Foundation of China （No. 30070307） and the National Special Fund for Doctoral Education ＆ Research Program, Ministry of Education, China （No. 20030698009）.

摘　　要：Background Few studies have explored the inward sodium current （INa） kinetics of transitional cardiomyocytes. This study aimed to explore the kinetics of transitional cardiomyocytes types α and β. Methods The whole-cell patch clamp technique was used to study the rapid INa of isolated transitional cardiomyocytes in the Koch triangle of rabbit hearts. Results Maximal amplitude and density of INa in type a and type β was （-1627±288） pA （α）, （-35.17±6.56） pA/pF （β） and （-3845±467） pA （α）, （-65.64±10.23） pA/pF （β） （P 〈0.05）. Steady state activation curves of INa, fitted to a Boltzmann distribution for both types, were sigmoid in shape. Half activation voltage and slope factors did not significantly differ between types at （-43.46±0.85） mV （α）, （-41.39±0.47） mV （β） or （9.04±0.66） mV （α）, （11.08±0.89） mV （β）. Steady state inactivation curves of INa, fitted to a Boltzmann distribution in both types were inverse ＂S＂ shape. Half inactivation voltage and slope factors were （-109.9±0.62） mV （α）, （-107.5±0.49） mV （β） and （11.78±0.36） mV （α）, （11.57±0.27） mV （β）, （P〉0.05）, but time constants of inactivation were significantly different at （1.10±0.19） mV （α） and （2.37±0.33） ms （β）, （P 〈0.05）. Time constants of recovery from inactivation of INa for both types were （122.16±27.43） mV （α） and （103.84±2.8.97） ms （β） （P 〈0.05）. Conclusions Transitional cardiomyocytes in rabbit hearts show a heterogeneous, voltage gated and time dependent fast inward sodium current. Types α and β show the features of INa similar to those in slow- and fast-response myocytes, with probably better automaticity and conductivity, respectively.Background Few studies have explored the inward sodium current （INa） kinetics of transitional cardiomyocytes. This study aimed to explore the kinetics of transitional cardiomyocytes types α and β. Methods The whole-cell patch clamp technique was used to study the rapid INa of isolated transitional cardiomyocytes in the Koch triangle of rabbit hearts. Results Maximal amplitude and density of INa in type a and type β was （-1627±288） pA （α）, （-35.17±6.56） pA/pF （β） and （-3845±467） pA （α）, （-65.64±10.23） pA/pF （β） （P 〈0.05）. Steady state activation curves of INa, fitted to a Boltzmann distribution for both types, were sigmoid in shape. Half activation voltage and slope factors did not significantly differ between types at （-43.46±0.85） mV （α）, （-41.39±0.47） mV （β） or （9.04±0.66） mV （α）, （11.08±0.89） mV （β）. Steady state inactivation curves of INa, fitted to a Boltzmann distribution in both types were inverse ＂S＂ shape. Half inactivation voltage and slope factors were （-109.9±0.62） mV （α）, （-107.5±0.49） mV （β） and （11.78±0.36） mV （α）, （11.57±0.27） mV （β）, （P〉0.05）, but time constants of inactivation were significantly different at （1.10±0.19） mV （α） and （2.37±0.33） ms （β）, （P 〈0.05）. Time constants of recovery from inactivation of INa for both types were （122.16±27.43） mV （α） and （103.84±2.8.97） ms （β） （P 〈0.05）. Conclusions Transitional cardiomyocytes in rabbit hearts show a heterogeneous, voltage gated and time dependent fast inward sodium current. Types α and β show the features of INa similar to those in slow- and fast-response myocytes, with probably better automaticity and conductivity, respectively.

关 键 词：sodium current transitional myocyte Koch triangle TACHYCARDIA 

分 类 号：R541[医药卫生—心血管疾病]