BACKGROUND: The aim of the present work was to study the profile of the rapid delayed rectifier potassium current (I (Kr)) and the inward rectifier potassium current (I (K1)) during ventricular repolarization as a function of action potential duration and rate of repolarization. METHODS: Whole cell configuration of the patch clamp technique was used to monitor I (Kr) and I (K1) during the action potential plateau and terminal repolarization. Action potentials recorded at various cycle lengths (0.4-5 s) and repolarizing voltage ramps having various slopes (0.5-3 V/s) were used as command signals. I (Kr) and I (K1) were identified as difference currents dissected by E-4031 and BaCl(2), respectively. RESULTS: Neither peak amplitudes nor mean values of I (Kr) and I (K1) recorded during the plateau of canine action potentials were influenced by action potential duration. The membrane potential where I (Kr) and I (K1) peaked during the terminal repolarization was also independent of action potential duration. Similar results were obtained in undiseased human ventricular myocytes, and also in canine cells when I (Kr) and I (K1) were evoked using repolarizing voltage ramps of various slopes. Action potential voltage clamp experiments revealed that the peak values of I (Kr), I (K1), and net outward current during the terminal repolarization were independent of the pacing cycle length within the range of 0.4 and 5 s. CONCLUSIONS: The results indicate that action potential configuration fails to influence the amplitude of I (Kr) and I (K1) during the ventricular action potential in dogs and humans, suggesting that rate-dependent changes in action potential duration are not likely related to rate-dependent alterations in I (Kr) or I (K1) kinetics in these species.
BACKGROUND: The aim of the present work was to study the profile of the rapid delayed rectifier potassium current (I (Kr)) and the inward rectifier potassium current (I (K1)) during ventricular repolarization as a function of action potential duration and rate of repolarization. METHODS: Whole cell configuration of the patch clamp technique was used to monitor I (Kr) and I (K1) during the action potential plateau and terminal repolarization. Action potentials recorded at various cycle lengths (0.4-5 s) and repolarizing voltage ramps having various slopes (0.5-3 V/s) were used as command signals. I (Kr) and I (K1) were identified as difference currents dissected by E-4031 and BaCl(2), respectively. RESULTS: Neither peak amplitudes nor mean values of I (Kr) and I (K1) recorded during the plateau of canine action potentials were influenced by action potential duration. The membrane potential where I (Kr) and I (K1) peaked during the terminal repolarization was also independent of action potential duration. Similar results were obtained in undiseased human ventricular myocytes, and also in canine cells when I (Kr) and I (K1) were evoked using repolarizing voltage ramps of various slopes. Action potential voltage clamp experiments revealed that the peak values of I (Kr), I (K1), and net outward current during the terminal repolarization were independent of the pacing cycle length within the range of 0.4 and 5 s. CONCLUSIONS: The results indicate that action potential configuration fails to influence the amplitude of I (Kr) and I (K1) during the ventricular action potential in dogs and humans, suggesting that rate-dependent changes in action potential duration are not likely related to rate-dependent alterations in I (Kr) or I (K1) kinetics in these species.
Authors: Ferenc Ruzsnavszky; Bence Hegyi; Kornél Kistamás; Krisztina Váczi; Balázs Horváth; Norbert Szentandrássy; Tamás Bányász; Péter P Nánási; János Magyar Journal: Naunyn Schmiedebergs Arch Pharmacol Date: 2014-02-25 Impact factor: 3.000
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: N Szentandrássy; V Farkas; L Bárándi; B Hegyi; F Ruzsnavszky; B Horváth; T Bányász; J Magyar; I Márton; P P Nánási Journal: Br J Pharmacol Date: 2012-10 Impact factor: 8.739
Authors: Tamás Hézső; Muhammad Naveed; Csaba Dienes; Dénes Kiss; János Prorok; Tamás Árpádffy-Lovas; Richárd Varga; Erika Fujii; Tanju Mercan; Leila Topal; Kornél Kistamás; Norbert Szentandrássy; János Almássy; Norbert Jost; János Magyar; Tamás Bányász; István Baczkó; András Varró; Péter P Nánási; László Virág; Balázs Horváth Journal: Sci Rep Date: 2021-05-05 Impact factor: 4.379
Authors: Maaike Hoekstra; Christine L Mummery; Arthur A M Wilde; Connie R Bezzina; Arie O Verkerk Journal: Front Physiol Date: 2012-08-31 Impact factor: 4.566