Title: Repolarizing K+ currents ITO1 and IKs are larger in right than left canine ventricular midmyocardium
Authors: Volders, P G ×
Sipido, Karin
Carmeliet, Edward
Spätjens, R L
Wellens, H J
Vos, M A #
Issue Date: 9-Feb-1999
Publisher: American Heart Association
Series Title: Circulation vol:99 issue:2 pages:206-10
Abstract: BACKGROUND: The ventricular action potential exhibits regional heterogeneity in configuration and duration (APD). Across the left ventricular (LV) free wall, this is explained by differences in repolarizing K+ currents. However, the ionic basis of electrical nonuniformity in the right ventricle (RV) versus the LV is poorly investigated. We examined transient outward (ITO1), delayed (IKs and IKr), and inward rectifier K+ currents (IK1) in relation to action potential characteristics of RV and LV midmyocardial (M) cells of the same adult canine hearts. METHODS AND RESULTS: Single RV and LV M cells were used for microelectrode recordings and whole-cell voltage clamping. Action potentials showed deeper notches, shorter APDs at 50% and 95% of repolarization, and less prolongation on slowing of the pacing rate in RV than LV. ITO1 density was significantly larger in RV than LV, whereas steady-state inactivation and rate of recovery were similar. IKs tail currents, measured at -25 mV and insensitive to almokalant (2 micromol/L), were considerably larger in RV than LV. IKr, measured as almokalant-sensitive tail currents at -50 mV, and IK1 were not different in the 2 ventricles. CONCLUSIONS: Differences in K+ currents may well explain the interventricular heterogeneity of action potentials in M layers of the canine heart. These results contribute to a further phenotyping of the ventricular action potential under physiological conditions.
ISSN: 0009-7322
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Cardiology
Experimental Cardiology
× corresponding author
# (joint) last author

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