Role of the Late Sodium Current in Rate-Dependent Repolarization of the Canine Ventricle

10.4077/CJP.2013.BAC194

Hong Zhang；Lin Yang；Zhao Yang；Xiao Zheng

action potential ； computer simulation ； late sodium current ； rate adaption ； transmural heterogeneity

The Chinese Journal of Physiology

56卷6期（2013 / 12 / 31）

341 - 348

英文

Late sodium current I(subscript NaL) is an inward current participating in maintaining the plateau of the action potential. So far its role in the repolarization of canine hearts is not well known. In this paper, by taking advantage of a computer simulation method, we developed a one-dimensional transmural tissue to study the impacts of I(subscript NaL) on rate-dependent repolarization and its ionic basis in the canine ventricle. An OpenMP parallel algorithm was performed on a four-core personal computer to accelerate the simulation. The results demonstrated that action potential durations of midmyocytes showed greater rate dependence than the endo- and epi-myocytes. When the pacing rate was reduced, repolarization of the tissue was prolonged while the transmural dispersion of repolarization (TDR) was enlarged. The enhancement of I(subscript NaL) further amplified this rate-dependent repolarization and TDR meanwhile increased the risk of arrhythmogenesis. I(subscript NaL) was found highly sensitive to the pacing rate by calculating its kinetics. The study suggested that I(subscript NaL) played an important role in the rate-dependent repolarization of the canine ventricle. Selective blockade of I(subscript NaL) could have clinical benefits, especially for such pathological conditions with enhanced I(subscript NaL) as long QT 3 syndrome and heart failure.

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