Affiliation:
1. Department of Biomedical Sciences and
2. Department of Physics, Cornell University, Ithaca, New York 14853-6401
Abstract
Although alternans of action potential duration (APD) is a robust feature of the rapidly paced canine ventricle, currently available ionic models of cardiac myocytes do not recreate this phenomenon. To address this problem, we developed a new ionic model using formulations of currents based on previous models and recent experimental data. Compared with existing models, the inward rectifier K+ current ( I K1) was decreased at depolarized potentials, the maximum conductance and rectification of the rapid component of the delayed rectifier K+ current ( I Kr) were increased, and I Kr activation kinetics were slowed. The slow component of the delayed rectifier K+current ( I Ks) was increased in magnitude and activation shifted to less positive voltages, and the L-type Ca2+ current ( I Ca) was modified to produce a smaller, more rapidly inactivating current. Finally, a simplified form of intracellular calcium dynamics was adopted. In this model, APD alternans occurred at cycle lengths = 150–210 ms, with a maximum alternans amplitude of 39 ms. APD alternans was suppressed by decreasing I Ca magnitude or calcium-induced inactivation and by increasing the magnitude of I K1, I Kr, or I Ks. These results establish an ionic basis for APD alternans, which should facilitate the development of pharmacological approaches to eliminating alternans.
Publisher
American Physiological Society
Subject
Physiology (medical),Cardiology and Cardiovascular Medicine,Physiology
Cited by
267 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献