Stimulation of Na+‐Ca2+ exchange by purified antibody against alpha‐2 repeat of Na+‐Ca2+ exchanger in rat cardiomyocytes

Aim: The aim of the present study was to investigate the effect of the antibody against alpha-2 repeat on Na + -Ca 2+ exchanger (NCX) current (I Na /Ca). To evaluate the functional specificity of this antibody, its effects on L-type Ca 2+ current (I Ca,L ), voltage-gated Na + current (I Na ) and delayed rectifier K+ current (I K ) were also observed. Methods: The whole-cell patch-clamp technique was used in this study. Results: The antibody against alpha-2 repeat augmented both the outward and inward Na + -Ca 2+ exchanger current concentration-dependently, with EC50 values of 27.9 nmol/L and 24.7 nmol/L, respectively. Meanwhile, the antibody could also increase I Ca,L in a concentration-dependent manner with the EC50 of 33.6 nmol/L. Effects of the antibody on I Na and I K were not observed in the present study. Conclusion: The present results suggest that antibody against alpha-2 repeat is a stimulating antibody to NCX and could also increase I Ca,L in a concentration-dependent manner, but did not have an obvious effect on I Na and I K .