Dependence of Na+-K+ pump current-voltage relationship on intracellular Na+, K+, and Cs+ in rabbit cardiac myocytes.
Am J Physiol Cell Physiol
; 283(5): C1511-21, 2002 Nov.
Article
em En
| MEDLINE
| ID: mdl-12372812
ABSTRACT
To examine effects of cytosolic Na+, K+, and Cs+ on the voltage dependence of the Na+-K+ pump, we measured Na+-K+ pump current (Ip) of ventricular myocytes voltage-clamped at potentials (Vm) from 100 to +60 mV. Superfusates were designed to eliminate voltage dependence at extracellular pump sites. The cytosolic compartment of myocytes was perfused with patch pipette solutions with a Na+ concentration ([Na]pip) of 80 mM and a K+ concentration from 0 to 80 mM or with solutions containing Na+ in concentrations from 0.1 to 100 mM and K+ in a concentration of either 0 or 80 mM. When [Na]pip was 80 mM, K+ in pipette solutions had a voltage-dependent inhibitory effect on Ip and induced a negative slope of the Ip-Vm relationship. Cs+ in pipette solutions had an effect on Ip qualitatively similar to that of K+. Increases in Ip with increases in [Na]pip were voltage dependent. The dielectric coefficient derived from [Na]pip-Ip relationships at the different test potentials was 0.15 when pipette solutions included 80 mM K+ and 0.06 when pipette solutions were K+ free.
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Bases de dados:
MEDLINE
Assunto principal:
Potássio
/
Sódio
/
Césio
/
ATPase Trocadora de Sódio-Potássio
/
Miocárdio
Limite:
Animals
Idioma:
En
Revista:
Am J Physiol Cell Physiol
Assunto da revista:
FISIOLOGIA
Ano de publicação:
2002
Tipo de documento:
Article
País de afiliação:
Austrália