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  • Title: [Characterisation of transient outward potassium current (Ito1) in hypertrophied right ventricular myocytes from children with tetralogy of Fallot].
    Author: Sun X, Hu X, Zhang B.
    Journal: Zhonghua Yi Xue Za Zhi; 2001 Oct; 81(19):1190-3. PubMed ID: 11769708.
    Abstract:
    OBJECTIVE: To investigate whether a transient outward potassium current exists in children hypertrophy ventricular myocytes and to characterize its basic electrophysiological properties. METHODS: Currents were recorded using whole-cell patch-clamp technique from enzymatically isolated ventricualr myocytes obtained from hearts of 10 patients aged 0.4-5 with tetralogy of Fallot (F4) ranging in age 0.4-5 years. RESULTS: In almost all cells studied, a Ito1 could be recorded on depolarization to between -20(-)+60 mV under conditions in which Ca2+ current was blocked. The current density is 4.7 PA/PF +/- 0.6 PA/PF at 60 mV. Its inactivation time constants under tested potential 0, 20, 40, 60 mV were 123 ms +/- 6 ms, 131 ms +/- 11 ms, 122 ms +/- 6 ms, 122 ms +/- 6 ms Half-maximal activation occurred at 4.1 mV +/- 2.8 mV. Half-maximal steady-state inactivation was -41 mV +/- 4 mV. Recovery from inactivation was voltage-dependent and the time course was 83 ms +/- 4 ms. CONCLUSION: A moderate Ca(2+)-independent transient outward K+ current is present in hypertrophied human ventricular myocytes from children with tetralogy of Fallot, its basic characteritics are similar to Ito1 observed in other species and human atria.
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