Effect on membrane potential and electrical activity of adding sodium to sodium-depleted cardiac purkinje fibers.
J Gen Physiol
; 64(4): 473-93, 1974 Oct.
Article
em En
| MEDLINE
| ID: mdl-4418558
ABSTRACT
Canine cardiac Purkinje fibers exposed to Na-free solutions containing 128 mM TEA and 16 mM Ca show resting potentials in the range -50 to -90 mV; if the concentration of Na in the perfusate is raised from 0 to 4 to 24 mM, hyperpolarization follows. If the initial resting potential is low, the hyperpolarization tends to be greater; the average increase in the presence of 8 mM Na is 14 mV. Such hyperpolarization is not induced by adding Na to K-free solutions, is not seen in cooled fibers, or in fibers exposed to 10(-3) M ouabain, nor is it induced by adding Li and thus may result from electrogenic sodium extrusion. Fibers exposed to Na-free solutions are often spontaneously active; if they are quiescent they often show repetitive activity during depolarizing pulses. Such spontaneous or repetitive activity is suppressed by the addition of Na. This suppression may or may not be related to the hyperpolarization.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Ramos Subendocárdicos
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Sódio
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Eletrofisiologia
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Coração
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Sistema de Condução Cardíaco
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Potenciais da Membrana
Limite:
Animals
Idioma:
En
Revista:
J Gen Physiol
Ano de publicação:
1974
Tipo de documento:
Article