Regulative effects of temperature, intracellular sodium, ATP and pH on I(Na/Ca) of cardiac myocytes / 生理学报
Acta Physiologica Sinica
;
(6): 136-140, 2006.
Article
Dans Chinois
| WPRIM
| ID: wpr-265474
ABSTRACT
The Na(+)-Ca(2+) exchange is a major pathway for removal of cytosolic Ca(2+) in cardiac myocytes. To explore the effects of temperature, intracellular Na(+), ATP and pH on Na(+)-Ca(2+) exchange currents (I(Na/Ca)) of intact guinea-pig myocytes, the whole-cell patch-clamp technique was used to record I(Na/Ca) in isolated guinea-pig ventricular myocytes. We found that I(Na/Ca) at 34 degrees C was four times higher than that at 22 degrees C. However, intracellular acidification had no obvious influence on bidirectional I(Na/Ca). At 22~24 degrees C , intracellular ATP depletion and intracellular acidification did not markedly affect bidirectional I(Na/Ca) either. At 34~37 degrees C , intracellular ATP depletion and intracellular acidification synergistically inhibited the outward and inward currents of I(Na/Ca), and blocked the inward currents of I(Na/Ca)more potently than the outward currents of I(Na/Ca). The effect of ATP on I(Na/Ca) is temperature-dependent. Intracellular higher sodium increased the outward currents of I(Na/Ca) however it did not increase, even sometimes decreased the inward currents of I(Na/Ca). These results suggest that intracellular ATP depletion and intracellular acidification synergistically impair Ca(2+) extrusion via forward mode Na(+)-Ca(2+) exchange, and intracellular sodium overload increases Ca(2+) influx via reverse mode Na(+)-Ca(2+) exchange, leading to calcium overload respectively.
Texte intégral:
Disponible
Indice:
WPRIM (Pacifique occidental)
Sujet Principal:
Anatomopathologie
/
Physiologie
/
Sodium
/
Température
/
Adénosine triphosphate
/
Calcium
/
Techniques de patch-clamp
/
Échangeur sodium-calcium
/
Biologie cellulaire
/
Myocytes cardiaques
Limites du sujet:
Animaux
langue:
Chinois
Texte intégral:
Acta Physiologica Sinica
Année:
2006
Type:
Article
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