التفاصيل البيبلوغرافية
| العنوان: |
Mathematical model of the rapidly activating delayed rectifier potassium current ikr in rabbit sinoatrial node. |
| المؤلفون: |
Oehmen CS, Giles WR, Demir SS |
| المصدر: |
Journal of Cardiovascular Electrophysiology; Nov2002, Vol. 13 Issue 11, p1131-1140, 10p |
| مستخلص: |
Introduction: A rapidly activating delayed rectifier potassium current (I[kappa]r) is known to have an important role in determining the properties of spontaneous pacing in enzymatically isolated rabbit sinoatrial node (SAN) cells. The functional characteristics of I[kappa]r are conferred by its dependence on time, voltage, and external potassium. The aim of this study was to develop a rigorous mathematical representation for I[kappa]r based on experimental findings and to investigate the role of I[kappa]r in the automaticity and intercellular communication of SAN cells. Methods and Results: A Markov model was developed using available experimental data for I[kappa]r in rabbit SAN. The dependence of I[kappa]r on external potassium, [K+]o, was incorporated using data from both in vitro preparations and results from heterologous expression experiments for this ether-a-go-go related gene product. Our simulation results show the following. (1) I[kappa]r is the dominant repolarizing current in rabbit SAN cells. (2) Deactivation of I[kappa]r contributes to the net current change during the early diastolic depolarization phase. (3) Inward rectification of I[kappa]r results in a decrease in membrane resistance during repolarization relative to plateau. (4) The complex [K+]o dependence of I[kappa]r confers [K+]o insensitivity on isolated cells, which may account for the sensitivity of pacing rate to elevated [K+]o at the tissue level. Conclusion: Model results show that I[kappa]r mediates diastolic depolarization by the kinetics of its decay and by lowering resistance during late repolarization. In elevated [K+]o, increased chord conductance is balanced by the changes in kinetics and voltage dependence of I[kappa]r so that the pacing rate of single cells may be more [K+]o insensitive than expected. In addition, elevated [K+]o increases I[kappa]r magnitude during repolarization but lowers resistance, so current flow through gap junctions is less able to hyperpolarize pacing cells. [ABSTRACT FROM AUTHOR] |
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| قاعدة البيانات: |
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