Jing Linyuan, Brownson Kathleen, Patwardhan Abhijit
Department of Biomedical Engineering, University of Kentucky, Lexington, KY, USA.
J Physiol Sci. 2014 May;64(3):185-93. doi: 10.1007/s12576-014-0310-2. Epub 2014 Mar 30.
Dynamics of repolarization, quantified as restitution and electrical memory, impact conduction stability. Relatively less is known about role of slow delayed rectifying potassium current, I(Ks), in dynamics of repolarization and memory compared to the rapidly activating current I(Kr). Trans-membrane potentials were recorded from right ventricular tissues from pigs during reduction (chromanol 293B) and increases in I(Ks) (mefenamic acid). A novel pacing protocol was used to explicitly control diastolic intervals to quantify memory. Restitution hysteresis, a consequence of memory, increased after chromanol 293B (loop thickness and area increased 27 and 38 %) and decreased after mefenamic acid (52 and 53 %). Standard and dynamic restitutions showed an increase in average slope after chromanol 293B and a decrease after mefenamic acid. Increase in slope and memory are hypothesized to have opposite effects on electrical stability; therefore, these results suggest that reduction and enhancement of I(Ks) likely also have offsetting components that affect stability.
复极化动力学，以恢复和电记忆来量化，会影响传导稳定性。与快速激活电流I(Kr)相比，关于缓慢延迟整流钾电流I(Ks)在复极化和记忆动力学中的作用，人们了解得相对较少。在降低I(Ks)（色满卡林293B）和增加I(Ks)（甲芬那酸）期间，记录了猪右心室组织的跨膜电位。采用了一种新颖的起搏方案来明确控制舒张间期以量化记忆。记忆的结果——恢复滞后，在色满卡林293B后增加（环厚度和面积分别增加27%和38%），而在甲芬那酸后减少（分别减少52%和53%）。标准恢复和动态恢复显示，在色满卡林293B后平均斜率增加，而在甲芬那酸后降低。斜率增加和记忆被认为对电稳定性有相反的影响；因此，这些结果表明，I(Ks)的降低和增强可能也有抵消性成分影响稳定性。
