Sodium-calcium exchange in heart: membrane currents and changes in [Ca2+]i.
Science
; 238(4834): 1720-2, 1987 Dec 18.
Article
em En
| MEDLINE
| ID: mdl-3686010
ABSTRACT
Recordings have been made of changes in intracellular calcium ion concentration ([Ca2+]i) that can be attributed to the operation of an electrogenic, voltage-dependent sodium-calcium (Na-Ca) exchanger in mammalian heart cells. Guinea pig ventricular myocytes under voltage clamp were perfused internally with fura-2, a fluorescent Ca2+-indicator, and changes in [Ca2+]i and membrane current that resulted from Na-Ca exchange were identified through the use of various organic channel blockers and impermeant ions. Depolarization of cells elicited slow increases in [Ca2+]i, with the maximum increase depending on internal [Na+], external [Ca2+], and membrane voltage. Repolarization was associated with net Ca2+ efflux and a decline in the inward current that developed instantaneously upon repolarization. The relation between [Ca2+]i and current was linear, and the slope was made steeper by hyperpolarization.
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Base de dados:
MEDLINE
Assunto principal:
Proteínas de Transporte
/
Cálcio
/
Coração
Tipo de estudo:
Prognostic_studies
Limite:
Animals
Idioma:
En
Ano de publicação:
1987
Tipo de documento:
Article