%0 Journal Article
%@ 0001-6772
%A  Varró András
%A  Nánási Péter Pál
%A  Lathrop DA
%A Élettani Intézet DE / ÁOK ElettI [2014-],
%A Farmakológiai és Farmakoterápiai Intézet SZTE / SZAOK FFI [2000-],
%D 1993
%F publicatio:32184
%J ACTA PHYSIOLOGICA SCANDINAVICA
%N 2
%P 133-142
%T Potassium currents in isolated human atrial and ventricular cardiocytes
%U http://publicatio.bibl.u-szeged.hu/32184/
%V 149
%X The whole-cell configuration of the patch-clamp technique was applied to study and compare ion currents in single ventricular and atrial cardiocytes isolated from human myocardium. In ventricular cardiocytes the K+ inward rectifier current (I(K1)) was three times larger than in atrial cardiocytes, while its inactivation kinetics were twice as slow when measured at - 140 mV. The magnitude of these variables depended on the test potential but was independent of changes in holding potential. A transient outward current (I(to)) was observed in both ventricular and atrial cardiocytes. The amplitude of the inactivating component of I(to) was not significantly different in atrial and ventricular cells, but the time course of inactivation was significantly longer in atrial than in ventricular cardiocytes. Steady-state inactivation of I(to) in atrial cells was well described by a two-state Boltzmann function having a midpoint potential of -41.4 mV and a slope factor of 6.9 mV-1. No discernible K+ delayed rectifier current (I(K)) was observed in either cell type. In four of the 12 atrial cells studied, a time dependent inward current was observed at negative test potentials having a 240 +/- 21 ms time constant for activation and an amplitude of 101 +/- 28 pA. This current, which resembled the pacemaker current (I(f)), was not observed in any of the ventricular cells examined.
%Z Departments of Pharmacology & Cell Biophysics and Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States                         Department of Pharmacology, Szent-Györgyi Albert Medical University, Szeged, Hungary                         Department of Physiology, University Medical School of Debrecen, Debrecen, Hungary                         Department of Medical Physiology, Institute of Medical Biology, University of Tromsø, Breivika, Tromsø, Norway              Correspondence Address: LATHROP, D.A.; Department of Medical Physiology, Imb, University of Tromsø, Breivika, MH-building, Tromsø, N-9037, Norway                         Chemicals/CAS: 4-Aminopyridine, 504-24-5; Potassium Channels