Impact of T-tubules on electrical activity of cardiac cells
evaluated in a quantitative model

a 2003

Impact of T-tubules on electrical activity of cardiac cells evaluated in a quantitative model

PÁSEK, Michal, Georges CHRISTÉ a Jiří ŠIMURDA

Základní údaje

Originální název

Impact of T-tubules on electrical activity of cardiac cells evaluated in a quantitative model

Autoři

PÁSEK, Michal (203 Česká republika, garant), Georges CHRISTÉ (250 Francie) a Jiří ŠIMURDA (203 Česká republika)

Vydání

3rd FEPS Congress -abstract book, 2003

Další údaje

Jazyk

angličtina

Typ výsledku

Konferenční abstrakt

Obor

10610 Biophysics

Stát vydavatele

Francie

Utajení

není předmětem státního či obchodního tajemství

Kód RIV

RIV/00216224:14110/03:00008681

Organizační jednotka

Lékařská fakulta

Klíčová slova anglicky

cardiac cell; tubular system; quantitative modelling

Štítky

Cardiac cell, Quantitative modelling, tubular system

Změněno: 1. 4. 2010 10:55, doc. Ing. Michal Pásek, Ph.D.

Anotace

V originále

We report here the first quantitative evaluation of the role of the transverse-axial tubular (TAT) system in the electrical activity of cardiac cells. Our approach uses a biophysically-based representation of the TAT-system incorporated into a model of cardiac ventricular cell (Jafri et al., Biophys. J. 1998, 74:1149-68). The model was modified to agree more closely with recent published data. The differential distribution of ion transfer mechanisms in peripheral and tubular membranes was included (e.g. K+ channels; Christé, J. Mol. Cell. Cardiol. 1999, 31:2207-13). Changes of ion concentrations in the TAT-lumen were computed from the total transmembrane ion fluxes and ion exchanges with the pericellular medium. Long term stability of the model was verified at rest and under regular stimulation, the charge conservation principle being respected. The tubular membrane voltage during an action potential was nearly identical with the peripheral membrane voltage, indicating that propagation of excitation along the TAT-system was quasi-instantaneous. Depletion of Ca2+ by 12.8 % and accumulation of K+ by 4.7 % occurred in the TAT-lumen during the course of an action potential at 1 Hz. However, the course of action potential was only slightly altered when the TAT-system was included into the model (shortening by less than 2 % at 90 % of repolarization). Under conditions of progressive hypokalaemia, the TAT-system retarded the occurrence of delayed after-depolarizations owing principally to Ca2+ depletion in the TAT-system and subsequently to suppression of Ca2+ overload in sarcoplasmic reticulum. They occurred at more severe hypokalaemia. These results show that modulation of the excitation-contraction coupling of ventricular cardiac tissue formerly attributed rather to narrow extracellular spaces is also an intrinsic property of the ventricular cardiac myocyte TAT-system, where the preferential localization of ion transfer mechanisms plays a key role.

Návaznosti

GP204/02/D129, projekt VaV

Název: Kvantitativní analýza vlivu tubulárního systému na elektrickou aktivitu srdečních buněk

Investor: Grantová agentura ČR, Kvantitativní analýza vlivu tubulárního systému na elektrickou aktivitu srdečních buněk

Citovat

PÁSEK, Michal, Georges CHRISTÉ a Jiří ŠIMURDA. Impact of T-tubules on electrical activity of cardiac cells evaluated in a quantitative model. In 3rd FEPS Congress -abstract book. 2003.

@proceedings{554939,
   author = {Pásek, Michal and Christé, Georges and Šimurda, Jiří},
   booktitle = {3rd FEPS Congress -abstract book},
   keywords = {cardiac cell; tubular system; quantitative modelling},
   language = {eng},
   title = {Impact of T-tubules on electrical activity of cardiac cells evaluated in a quantitative model},
   year = {2003}
}

TY  - CONF
ID  - 554939
AU  - Pásek, Michal - Christé, Georges - Šimurda, Jiří
PY  - 2003
TI  - Impact of T-tubules on electrical activity of cardiac cells evaluated in a quantitative model
KW  - cardiac cell
KW  - tubular system
KW  - quantitative modelling
N2  - We report here the first quantitative evaluation of the role of the transverse-axial tubular (TAT) system in the electrical activity of cardiac cells. Our approach uses a biophysically-based representation of the TAT-system incorporated into a model of cardiac ventricular cell (Jafri et al., Biophys. J. 1998, 74:1149-68). The model was modified to agree more closely with recent published data. The differential distribution of ion transfer mechanisms in peripheral and tubular membranes was included (e.g. K+ channels; Christé, J. Mol. Cell. Cardiol. 1999, 31:2207-13). Changes of ion concentrations in the TAT-lumen were computed from the total transmembrane ion fluxes and ion exchanges with the pericellular medium. Long term stability of the model was verified at rest and under regular stimulation, the charge conservation principle being respected. The tubular membrane voltage during an action potential was nearly identical with the peripheral membrane voltage, indicating that propagation of excitation along the TAT-system was quasi-instantaneous. Depletion of Ca2+ by 12.8 % and accumulation of K+ by 4.7 % occurred in the TAT-lumen during the course of an action potential at 1 Hz. However, the course of action potential was only slightly altered when the TAT-system was included into the model (shortening by less than 2 % at 90 % of repolarization). Under conditions of progressive hypokalaemia, the TAT-system retarded the occurrence of delayed after-depolarizations owing principally to Ca2+ depletion in the TAT-system and subsequently to suppression of Ca2+ overload in sarcoplasmic reticulum. They occurred at more severe hypokalaemia. These results show that modulation of the excitation-contraction coupling of ventricular cardiac tissue formerly attributed rather to narrow extracellular spaces is also an intrinsic property of the ventricular cardiac myocyte TAT-system, where the preferential localization of ion transfer mechanisms plays a key role.
ER  -

PÁSEK, Michal, Georges CHRISTÉ a Jiří ŠIMURDA. Impact of T-tubules on electrical activity of cardiac cells evaluated in a quantitative model. In \textit{3rd FEPS Congress -abstract book}. 2003.

Podrobný výpis o publikaci