May 15, 2003Journal of Clinical Investigation
Functional role of inward rectifier current in heart probed by Kir2.1 overexpression and dominant-negative suppression
Why the study?
Does Kir2.1 overexpression or suppression alter cardiac repolarization and resting membrane potential in guinea pig ventricular myocytes?
Population
Guinea pig ventricular myocytes and animals (n=4 for Kir2.1-transduced, n=3 for Kir2.1AAA-transduced)
Comparison
In vivo viral gene transfer of Kir2.1 or… vs Control cells and immediate postoperative ECG…
Design
Preclinical
Follow-up
72 hours after gene delivery
Authors
Discussion
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Implication
Extends IK1's role in repolarization to guinea pig models; leaves open translation to human long-QT syndromes.
Key Points
- To investigate the functional role of the inward rectifier potassium current (IK1) in cardiac repolarization and resting membrane potential maintenance in ventricular myocytes.
- Transduced guinea pig ventricular myocytes in vivo with viral vectors carrying Kir2.1 to overexpress IK1 or dominant-negative Kir2.1AAA to suppress IK1.
- Assessed cellular electrophysiology—including barium-sensitive IK1, action potential durations, and resting membrane potential—alongside surface ECGs at baseline and 72 hours post-transfer (Kir2.1, n=4; Kir2.1AAA, n=3).
- Kir2.1 overexpression boosted barium-sensitive IK1 by more than 100% at -50 mV, hyperpolarized resting membrane potential, accelerated phase 3 repolarization, and shortened the QTc interval by 7.7% ± 0.9% (n=4).
- Dominant-negative Kir2.1AAA reduced IK1 by 50% to 90%, depolarized resting membrane potential, prolonged action potential durations, and lengthened the QTc interval by 16.7% ± 1.8% (n=3), with profound suppression inducing a pacemaker phenotype.
Structured PICO
Does Kir2.1 overexpression or suppression alter cardiac repolarization and resting membrane potential in guinea pig ventricular myocytes?
P
Population
Guinea pig ventricular myocytes and animals (n=4 for Kir2.1-transduced, n=3 for Kir2.1AAA-transduced)
I
Intervention
In vivo viral gene transfer of Kir2.1 (overexpression) or dominant-negative Kir2.1AAA (suppression)
C
Comparator
Control cells (nongreen cells from the same hearts and green cells from GFP-transduced hearts) and immediate postoperative ECG recordings
O
Outcome
Cardiac repolarization, resting membrane potential (RMP), action potential durations (APDs), and QTc intervalsurrogate
IK1 is essential for rapid terminal repolarization and stable resting potential in ventricular myocytes, and its suppression directly causes the long-QT phenotype seen in Andersen syndrome.
Cite This Study
Miake et al. (2003) studied this question.