Voltage noise influences action potential duration in cardiac myocytes.
Stochastic gating of ion channels introduces noise to membrane currents in cardiac muscle cells (myocytes). Since membrane currents drive membrane potential, noise thereby influences action potential duration (APD) in myocytes. To assess the influence of noise on APD, membrane potential is in this study formulated as a stochastic process known as a diffusion process, which describes both the current-voltage relationship and voltage noise. In this framework, the response of APD voltage noise and the dependence of response on the shape of the current-voltage relationship can be characterized analytically. We find that in response to an increase in noise level, action potential in a canine ventricular myocytes is typically prolonged and that distribution of APDs becomes more skewed towards long APDs, which may lead to an increased frequency of early after-depolarization formation. This is a novel mechanism by which voltage noise may influence APD. The results are in good agreement with those obtained from more biophysically-detailed mathematical models, and increased voltage noise (due to gating noise) may partially underlie an increased incidence of early after-depolarizations in heart failure.
Tanskanen
Antti J
AJ
Institute for Computational Medicine and the Center for Cardiovascular Bioinformatics and Modeling, The Johns Hopkins University School of Medicine and Whiting School of Engineering, Baltimore, MD 21218, USA. atanskan@bme.jhu.edu
Alvarez
Luis H R
LH
D000200:Action Potentials / Q000502:physiology*; D000465:Algorithms; D000818:Animals; D020746:Calcium Channels, L-Type / Q000502:physiology; D003198:Computer Simulation; D004285:Dogs; D004594:Electrophysiology; D015640:Ion Channel Gating / Q000502:physiology; D008564:Membrane Potentials / Q000502:physiology; D008954:Models, Biological; D032383:Myocytes, Cardiac / Q000502:physiology*; D016008:Statistical Distributions; D013269:Stochastic Processes; D013997:Time Factors
D020746:Calcium Channels, L-Type