Key result
Diastolic outward K+ current iKdd separates from pacemaker current i(f) in Purkinje myocytes.
Why the study?
Some findings challenge the assumption that the hyperpolarization activated inward current i(f) underlies the pacemaker potential in cardiac Purkinje fibers.
Population
Single canine Purkinje myocytes
Comparison
Currents under varying ionic conditions including Tyrode solution, different [K+]o, Cs+, and Ba2+
Design
Whole cell patch clamp study
Authors
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May inform Purkinje automaticity mechanisms; leaves open human arrhythmogenic relevance pending translational data.
Demonstrates the existence of a distinct voltage- and time-dependent K+ current (iKdd) in canine Purkinje myocytes that contributes to diastolic depolarization, separate from the i(f) current.
Vassalle et al. (1995) studied this question. Whole cell patch clamp with ion manipulation (Ba2+, Cs+, K+) was evaluated on Pacemaker current characteristics (iKdd and i(f)). In canine Purkinje myocytes, there is a voltage- and time-dependent K+ current (iKdd) in the diastolic range of potentials that can be separated from the hyperpolarization-activated inward current i(f).
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