Modulation of cytosolic and nuclear Ca2+ and Na+ transport by taurine in heart cells.
The effect of taurine on the different types of ionic currents appears to depend on [Ca]o and [Ca]i and may also vary accordingly to tissue or cell type studied. Using microfluorometry and Ca2+ imaging techniques, short-term exposure (5-10 min) of single heart cells to taurine was found to increase total intracellular free Ca2+ in a concentration-dependent manner. However, long-term exposure of heart myocytes to taurine was found to decrease both nuclear and cytosolic Ca2+ without significantly changing either nuclear or cytosolic Na+ levels, as measured by 3-dimensional Ca2+ and Na+ confocal imaging techniques. Long-term exposure to taurine was found to prevent cytosolic and nuclear increases of Ca2+ induced by permanent depolarization of heart cells with high [K]o. This preventive effect of taurine on nuclear Ca2+ overload was associated with an increase of both cytosolic and nuclear free Na+. Thus, the effect of long-term exposure to taurine on intranuclear Ca2+ overload in heart cells seems to be mediated via stimulation of sarcolemmal and nuclear Ca2+ outflow through the Na+-Ca2+ exchanger.
Bkaily
G
G
Department of Anatomy and Cell Biology, Faculty of Medicine, Université de Sherbrooke, Quebec, Canada.
Jaalouk
D
D
Haddad
G
G
Gros-Louis
N
N
Simaan
M
M
Naik
R
R
Pothier
P
P
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism*; D002642:Chick Embryo; D003600:Cytosol / Q000378:metabolism; D005456:Fluorescent Dyes; D016257:Fura-2 / Q000031:analogs & derivatives; D006352:Heart Ventricles; D007700:Kinetics; D018613:Microscopy, Confocal; D009206:Myocardium / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism*; D013654:Taurine / Q000494:pharmacology*
D005456:Fluorescent Dyes; C049925:fura-2-am; D013654:Taurine; D012964:Sodium; D002118:Calcium; D016257:Fura-2