Medizinische Universität Graz Austria/Österreich - Forschungsportal - Medical University of Graz
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SHR Neuro Krebs Kardio Lipid Stoffw Microb
Krogh-Madsen, T; Schaffer, P; Skriver, AD; Taylor, LK; Pelzmann, B; Koidl, B; Guevara, MR.
An ionic model for rhythmic activity in small clusters of embryonic chick ventricular cells.
Am J Physiol Heart Circ Physiol. 2005; 289(1):H398-H413
Doi: 10.1152/ajpheart.00683.2004
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- Co-Autor*innen der Med Uni Graz
- Pelzmann Brigitte
- Schaffer Peter
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- Abstract:
- We recorded transmembrane potential in whole cell recording mode from small clusters (2-4 cells) of spontaneously beating 7-day embryonic chick ventricular cells after 1-3 days in culture and investigated effects of the blockers D-600, diltiazem, almokalant, and Ba2+. Electrical activity in small clusters is very different from that in reaggregates of several hundred embryonic chick ventricular cells, e.g., TTX-sensitive fast upstrokes in reaggregates vs. TTX-insensitive slow upstrokes in small clusters (maximum upstroke velocity approximately 100 V/s vs. approximately 10 V/s). On the basis of our voltage- and current-clamp results and data from the literature, we formulated a Hodgkin-Huxley-type ionic model for the electrical activity in these small clusters. The model contains a Ca2+ current (ICa), three K+ currents (IKs, IKr, and IK1), a background current, and a seal-leak current. ICa generates the slow upstroke, whereas IKs, IKr, and IK1 contribute to repolarization. All the currents contribute to spontaneous diastolic depolarization, e.g., removal of the seal-leak current increases the interbeat interval from 392 to 535 ms. The model replicates the spontaneous activity in the clusters as well as the experimental results of application of blockers. Bifurcation analysis and simulations with the model predict that annihilation and single-pulse triggering should occur with partial block of ICa. Embryonic chick ventricular cells have been used as an experimental model to investigate various aspects of spontaneous beating of cardiac cells, e.g., mutual synchronization, regularity of beating, and spontaneous initiation and termination of reentrant rhythms; our model allows investigation of these topics through numerical simulation.
- Find related publications in this database (using NLM MeSH Indexing)
- Action Potentials - physiology
- Animals -
- Anti-Arrhythmia Agents - pharmacology
- Barium - pharmacology
- Biological Clocks - physiology
- Calcium Channel Blockers - pharmacology
- Calcium Channels - physiology
- Chick Embryo -
- Computer Simulation -
- Electric Conductivity -
- Gallopamil - pharmacology
- Homeostasis -
- Ions -
- Models, Cardiovascular -
- Myocytes, Cardiac - drug effects Myocytes, Cardiac - physiology
- Patch-Clamp Techniques -
- Periodicity -
- Potassium Channels - physiology
- Propanolamines - pharmacology
- Ventricular Function -
- Find related publications in this database (Keywords)
- pacemaker
- seal-leak current
- rapid delayed rectifier potassium current block
- slow inward calcium current block
- bifurcation analysis