Varshneya M, Devenyi RA, Sobie EA. Slow Delayed Rectifier Current Protects Ventricular Myocytes From Arrhythmic Dynamics Across Multiple Species: A Computational Study.
Circ Arrhythm Electrophysiol 2019;
11:e006558. [PMID:
30354408 DOI:
10.1161/circep.118.006558]
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Abstract
BACKGROUND
The slow and rapid delayed rectifier K+ currents (IKs and IKr, respectively) are responsible for repolarizing the ventricular action potential (AP) and preventing abnormally long APs that may lead to arrhythmias. Although differences in biophysical properties of the 2 currents have been carefully documented, the respective physiological roles of IKr and IKs are less established. In this study, we sought to understand the individual roles of these currents and quantify how effectively each stabilizes the AP and protects cells against arrhythmias across multiple species.
METHODS
We compared 10 mathematical models describing ventricular myocytes from human, rabbit, dog, and guinea pig. We examined variability within heterogeneous cell populations, tested the susceptibility of cells to proarrhythmic behavior, and studied how IKs and IKr responded to changes in the AP.
RESULTS
We found that (1) models with higher baseline IKs exhibited less cell-to-cell variability in AP duration; (2) models with higher baseline IKs were less susceptible to early afterdepolarizations induced by depolarizing perturbations; (3) as AP duration is lengthened, IKs increases more profoundly than IKr, thereby providing negative feedback that resists excessive AP prolongation; and (4) the increase in IKs that occurs during β-adrenergic stimulation is critical for protecting cardiac myocytes from early afterdepolarizations under these conditions.
CONCLUSIONS
Slow delayed rectifier current is uniformly protective across a variety of cell types. These results suggest that IKs enhancement could potentially be an effective antiarrhythmic strategy.
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