| Objective: To explore the electrophysiological basis of arrhythmogenesis in right ventricular outflow tract(RVOT) myocytes of rabbit heart, the properties of action potential (AP) and sodium-calcium exchange tail current(INCX,tail) in rabbit RVOT cells were observed.Methods: Langendorff apparatus and Patch-clamp technique were used to measure INCX,tail and AP in single right ventricular (RV) and RVOT myocytes obtained by enzymatic dispersion of rabbit ventricle.Results: Marked variability of action potential (AP) repolarization duration was observed in rabbit RVOT cardiomyocytes. The events of early afterdepolarization (EAD) and marked extension of action potential duration (APD) were recorded in RVOT cells. The peak of INCX,tail was delayed significantly in marked APD extension RVOT cells group compare to RV free wall cell group, and the amplitude of INCX,tail in the former was larger than the latter ones [(155.60±46.55) pA vs(96.13±54.68)pA] (P<0.05). Conclusion: In rabbit RVOT cardiomyocytes, marked prolonged APD might be the induction factor of DAD and EAD genesis. Under this precondition, the late-peaking and larger amplitude of INCX,tail in RVOT cells compare to RV Free-wall cells might be in that NCX arise larger transient inward current in later period of APD along with the enhanced L-type calcium current.It mighe be the electrophysiological basis of triggered activity in RVOT cardiomyocytes. In conclusion, the activity of NCX should work in the match manner with the rise and relaxion of contraction, otherwise it might be arrythmogenic even in a physiological heart.NCX might perform a particularly essential function in RVOT arrhythmogenesis. |
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