期刊
PROGRESS IN BIOPHYSICS & MOLECULAR BIOLOGY
卷 96, 期 1-3, 页码 258-280出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.pbiomolbio.2007.07.022
关键词
t-tubule; ion accumulation; ion depletion; extracellular space; TATS; restricted diffusion; heart; ventricle; myocyte; model; guinea-pig
资金
- British Heart Foundation Funding Source: Medline
- Wellcome Trust Funding Source: Medline
A model of the guinea-pig cardiac ventricular myocyte has been developed that includes a representation of the transverse-axial tubular system (TATS), including heterogeneous distribution of ion flux pathways between the surface and tubular membranes. The model reproduces frequency-dependent changes of action potential shape and intracellular ion concentrations and can replicate experimental data showing ion diffusion between the tubular lumen and external solution in guinea-pig myocytes. The model is stable at rest and during activity and returns to rested state after perturbation. Theoretical analysis and model simulations show that, due to tight electrical coupling, tubular and surface membranes behave as a homogeneous whole during voltage and current clamp (maximum difference 0.9mV at peak tubular I-Na of -38 nA). However, during action potentials, restricted diffusion and ionic currents in TATS cause depletion of tubular Ca2+ and accumulation of tubular K+ (up to -19.8% and +3.4%, respectively, of bulk extracellular values, at 6 Hz). These changes, in turn, decrease ion fluxes across the TATS membrane and decrease sarcoplasmic reticulum (SR) Ca2+ load. Thus, the TATS plays a potentially important role in modulating the function of guinea-pig ventricular myocyte in physiological conditions. (C) 2007 Elsevier Ltd. All rights reserved.
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