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BACKGROUND Cardiac memory (CM) refers to T-wave changes induced by ventricular pacing or arrhythmia that accumulate in magnitude and duration with repeated episodes of abnormal activation. We report herein the kinetics of long-term CM and its association with the ventricular action potential. METHODS AND RESULTS Dogs were paced from the ventricles at(More)
The purpose of this study was to determine whether oligonucleotides the size of siRNA are permeable to gap junctions and whether a specific siRNA for DNA polymerase beta (pol beta) can move from one cell to another via gap junctions, thus allowing one cell to inhibit gene expression in another cell directly. To test this hypothesis, fluorescently labelled(More)
BACKGROUND In depolarized myocardial infarct epicardial border zones, the cardiac sodium channel (SCN5A) is largely inactivated, contributing to low action potential upstroke velocity (V(max)), slow conduction, and reentry. We hypothesized that a fast inward current such as the skeletal muscle sodium channel (SkM1) operating more effectively at depolarized(More)
INTRODUCTION Cultured neonatal rat ventricular myocytes (NRVM) reestablish gap junctions as they form synchronously and spontaneously beating monolayers, thus providing a useful model for studying activation and repolarization. METHODS AND RESULTS We used the multielectrode array data acquisition system with 60 unipolar electrodes to investigate the(More)
Isolated canine Purkinje fiber bundles (PF) were perfused with the blood of intact donor dogs to correlate changes induced by ouabain (0) in the PF transmembrane potential (TP) and the donor ECG. 0 was administered intravenously to the donor, and standard microelectrode technics were used to record the TP. The only significant 0 effect prior to occurrence(More)
OBJECTIVE Our goal was to study rate adaptation of atrial action potentials in non-steady and steady states to further our understanding of mechanisms determining inducibility and stability of atrial fibrillation. METHODS We used standard microelectrode techniques to examine the characteristics of steady-state action potentials paced at regular cycle(More)
Endothelin-1 (ET-1) is an important contributor to ventricular hypertrophy and failure, which are associated with arrhythmogenesis and sudden death. To elucidate the mechanism(s) underlying the arrhythmogenic effects of ET-1 we tested the hypothesis that long-term (24 hrs) exposure to ET-1 impairs impulse conduction in cultures of neonatal rat ventricular(More)
Complex modulation of voltage-gated Ca2+ currents through the interplay among Ca2+ channels and various Ca(2+)-binding proteins is increasingly being recognized. The K+ channel interacting protein 2 (KChIP2), originally identified as an auxiliary subunit for K(V)4.2 and a component of the transient outward K+ channel (I(to)), is a Ca(2+)-binding protein(More)
We used open tip microelectrodes containing a K+-sensitive liquid ion exchanger to determine directly the intracellular K+ activity in beating canine cardiac Purkinje fibers. For preparations superfused with Tyrode's solution in which the K+ concentration was 4.0 mM, intracellular K+ activity (ak) was 130.0+/-2.3 mM (mean+/-SE) at 37 degrees C. The(More)