Role of Individual Ionic Current Systems in Ventricular Cells Hypothesized by a Model Study

• Matsuoka Satoshi

  Department of Physiology and Biophysics, Kyoto University Graduate School of Medicine

• Sarai Nobuaki

• Kuratomi Shinobu

• Ono Kyoichi

• Noma Akinori

Abstract

Individual ion channels or exchangers are described with a common set of equetions for both the sinoatrial node pacemaker and ventricular cells. New experimental data are included, such as the new kinetics of the inward rectifier K⁺ channel, delayed rectifier K⁺ channel, and sustained inward current. The gating model of Shirokov et al. (J Gen Physiol 102: 1005–1030, 1993) is used for both the fast Na⁺ and L-type Ca²⁺ channels. When combined with a contraction model (Negroni and Lascano: J Mol Cell Cardiol 28: 915–929, 1996), the experimental staircase phenomenon of contraction is reconstructed. The modulation of the action potential by varying the external Ca²⁺ and K⁺ concentrations is well simulated. The conductance of I_CaL dominates membrane conductance during the action potential so that an artificial increase of I_to, I_Kr, I_Ks, or I_KATP magnifies I_CaL amplitude. Repolarizing current is provided sequentially by I_Ks, I_Kr, and I_K1. Depression of ATP production results in the shortening of action potential through the activation of I_KATP. The ratio of Ca²⁺ released from SR over Ca²⁺ entering via I_CaL (Ca²⁺ gain = ∼15) in excitation-contraction coupling well agrees with the experimental data. The model serves as a predictive tool in generating testable hypotheses.<br>

Journal

• The Japanese Journal of Physiology

  The Japanese Journal of Physiology 53 (2), 105-123, 2003

  THE PHYSIOLOGICAL SOCIETY OF JAPAN

Keywords

• cardiac ventricular cell model
• excitation contraction coupling
• ion channel model
• ion exchanger model

Details

• CRID: 1390282680018130816
• NII Article ID: 10011229678
• NII Article ID: 130004435862
• NII Book ID: AA00691224
• DOI: 10.2170/jjphysiol.53.105
• COI: 1:CAS:528:DC%2BD3sXmslOqsrY%3D
• ISSN: 18811396
• ISSN: 0021521X
• NDL BIB ID: 6610439
• PubMed: 12877767
• Web Site: http://id.ndl.go.jp/bib/6610439
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I6610439
• Web Site: https://search.jamas.or.jp/link/ui/2004037084
• Text Lang: en
• Data Source:
  • JaLC
  • NDL
  • Crossref
  • PubMed
  • CiNii Articles
• Abstract License Flag: Disallowed