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Inhibitory effects of purified antibody against -1 repeat (117-137) on Na+-Ca2+ exchange and L-type Ca2+ currents in rat cardiomyocytes

FENG Qi-Long, WU Dong-Mei, CUI Xiang-Li, ZHAO Hua-Chen, LIN Yuan-Yuan, ZHAO Lu-Ying, WU Bo-Wei

Department of Physiology； Department of Pharmacology, Shanxi Medical University, Taiyuan 030001, China； 3Key Laboratory of Cellular Physiology, Shanxi Province and Ministry of Education, Taiyuan 030001, China； 4Beijing Cord Blood Bank, Beijing 100176, China

Abstract

Considering that α-1 repeat region may be involved in the ion binding and translocation of Na+-Ca2+ exchanger (NCX), it ispossible that the antibodies against NCX α-1 repeat may have a crucial action on NCX activity. The aim of the present study is toinvestigate the effect of antibody against α-1 repeat (117-137), designated as α-1(117-137), on NCX activity. The antibody against thesynthesized α-1(117-137) was prepared and affinity-purified. Whole-cell patch clamp technique was used to study the change of Na+-Ca2+ exchange current (INa/Ca) in adult rat cardiomyocytes. To evaluate the functional specificity of this antibody, its effects on L-typeCa2+ current (ICa,L), voltage-gated Na+ current (INa) and delayed rectifier K+ current (IK) were also observed. The amino acid sequences ofα-1(117-137) in NCX and residues 1 076-1 096 within L-type Ca2+ channel were compared using EMBOSS Pairwise AlignmentAlgorithms. The results showed that outward and inward INa/Ca were decreased by the antibody against α-1(117-137) dose-dependentlyin the concentration range from 10 to 160 nmol/L, with IC50 values of 18.9 nmol/L and 22.4 nmol/L, respectively. Meanwhile, theantibody also decreased ICa,L in a concentration-dependent manner with IC50 of 22.7 nmol/L. No obvious effects of the antibody on INaand IK were observed. Moreover, comparison of the amino acid sequences showed there was 23.8% sequence similarity between NCXα-1(117-137) and residues 1 076-1 096 within L-type Ca2+ channel. These results suggest that antibody against α-1(117-137) is a blockingantibody to NCX and can also decrease ICa,L in a concentration-dependent manner, while it does not have obvious effects on INa and IK.

Key words: sodium-calcium exchanger; patch-clamp technique; cardiac myocytes; antibody

Received: 2010-06-24　　Accepted: 2010-09-14

Corresponding author: 吴博威　　E-mail: wubowei299@sohu.com

Citing This Article：

FENG Qi-Long, WU Dong-Mei, CUI Xiang-Li, ZHAO Hua-Chen, LIN Yuan-Yuan, ZHAO Lu-Ying, WU Bo-Wei. Inhibitory effects of purified antibody against -1 repeat (117-137) on Na+-Ca2+ exchange and L-type Ca2+ currents in rat cardiomyocytes. Acta Physiol Sin 2010; 62 (5): 407-414 (in Chinese with English abstract).