OBJECTIVE: It was the aim of our study to describe repolarizing currents in ventricular myocytes isolated from children with tetralogy of Fallot. This is the first report on outward currents in ventricular myocytes from children. METHODS: Ventricular myocytes were isolated from tissue samples of the outflow tract of the right ventricle which were obtained during corrective surgery of tetralogy of Fallot. Action potentials and whole-cell currents were recorded with the patch clamp technique at a temperature of 36-37 degrees C. RESULTS: The mean resting potential was -71.7 +/- 1.92 mV, action potential amplitude was 110 +/- 2.96 mV and action potential duration at 90% repolarization was 794 +/- 99.5 ms (n = 12). In four out of 12 myocytes early afterdepolarizations (EADs) were observed. Upon hyperpolarization Ba(2+)-sensitive inward currents similar to the inward rectifier current (IKl) could be observed. The current density at -120 mV was -22.8 +/- 2.47 pA/pF (n = 14). A transient outward current (Itol) could be recorded in all myocytes studied, the current density varied from 0.3 to 8.6 pA/pF with a mean of 3.77 +/- 0.47 pA/pF at +40 mV (n = 38). Recovery of Itol from inactivation was fast (70% recovery within 100 ms), rate-dependent reduction amounted to 38.2% at 4 Hz. A delayed rectifier current was seen in only two out of 38 myocytes (rapid component IKr). CONCLUSIONS: The electrophysiological characteristics of right ventricular myocytes isolated from children with tetralogy of Fallot resemble in most cases subendocardial myocytes from adults. The most prominent difference is a fast recovery from inactivation as well as a small rate dependent reduction of Itol. The observed EADs may have clinical implications.
OBJECTIVE: It was the aim of our study to describe repolarizing currents in ventricular myocytes isolated from children with tetralogy of Fallot. This is the first report on outward currents in ventricular myocytes from children. METHODS: Ventricular myocytes were isolated from tissue samples of the outflow tract of the right ventricle which were obtained during corrective surgery of tetralogy of Fallot. Action potentials and whole-cell currents were recorded with the patch clamp technique at a temperature of 36-37 degrees C. RESULTS: The mean resting potential was -71.7 +/- 1.92 mV, action potential amplitude was 110 +/- 2.96 mV and action potential duration at 90% repolarization was 794 +/- 99.5 ms (n = 12). In four out of 12 myocytes early afterdepolarizations (EADs) were observed. Upon hyperpolarization Ba(2+)-sensitive inward currents similar to the inward rectifier current (IKl) could be observed. The current density at -120 mV was -22.8 +/- 2.47 pA/pF (n = 14). A transient outward current (Itol) could be recorded in all myocytes studied, the current density varied from 0.3 to 8.6 pA/pF with a mean of 3.77 +/- 0.47 pA/pF at +40 mV (n = 38). Recovery of Itol from inactivation was fast (70% recovery within 100 ms), rate-dependent reduction amounted to 38.2% at 4 Hz. A delayed rectifier current was seen in only two out of 38 myocytes (rapid component IKr). CONCLUSIONS: The electrophysiological characteristics of right ventricular myocytes isolated from children with tetralogy of Fallot resemble in most cases subendocardial myocytes from adults. The most prominent difference is a fast recovery from inactivation as well as a small rate dependent reduction of Itol. The observed EADs may have clinical implications.
Authors: Junyi Ma; Liang Guo; Steve J Fiene; Blake D Anson; James A Thomson; Timothy J Kamp; Kyle L Kolaja; Bradley J Swanson; Craig T January Journal: Am J Physiol Heart Circ Physiol Date: 2011-09-02 Impact factor: 4.733
Authors: Rosalie M E Meijer van Putten; Isabella Mengarelli; Kaomei Guan; Jan G Zegers; Antoni C G van Ginneken; Arie O Verkerk; Ronald Wilders Journal: Front Physiol Date: 2015-02-03 Impact factor: 4.566
Authors: Jan Trieschmann; Moritz Haustein; Annette Köster; Jürgen Hescheler; Konrad Brockmeier; Gerardus Bennink; Tobias Hannes Journal: Stem Cells Int Date: 2019-03-06 Impact factor: 5.443