[Characterisation of transient outward potassium current (Ito1) in hypertrophied right ventricular myocytes from children with tetralogy of Fallot].
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.


CONCLUSIONS
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.
Sun
X
X
Department of Anesthesiology, Beijing Tongren Hospital, Capital University of Medical Sciences, Beijing 100730, China.
Hu
X
X
Zhang
B
B
D002675:Child, Preschool; D004558:Electric Stimulation; D005260:Female; D006801:Humans; D017380:Hypertrophy, Right Ventricular / Q000473:pathology / Q000503:physiopathology*; D007223:Infant; D008297:Male; D008564:Membrane Potentials / Q000502:physiology; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000502:physiology*; D013771:Tetralogy of Fallot / Q000503:physiopathology*; D013997:Time Factors
D015221:Potassium Channels