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.
|Number of pages||9|
|Journal||Journal of Physiological Sciences|
|State||Published - May 2014|
Bibliographical noteFunding Information:
Acknowledgement Supported by grants from the National Science Foundation (0730450, 0814194) and the Commonwealth of Kentucky.
- Action potential duration
- Cardiac memory
- Slow delayed rectifier potassium current
- Ventricular arrhythmia
ASJC Scopus subject areas