Aging: stimulation rate on cardiac intracellular Na+ activity and developed tension.
Mech Ageing Dev
; 60(3): 303-13, 1991 Nov 01.
Article
em En
| MEDLINE
| ID: mdl-1661359
ABSTRACT
Previous reports suggested that Na,K-ATPase activity and Na(+)-pump capacity decrease with senescence in left atrial myocardium of F344 rats. Current experiments were designed to determine if this reduction in the Na(+)-pump affects free intracellular Na+ levels. Mean intracellular Na+ ion activity (aiNa) was measured with Na-selective microelectrodes in left atrial muscle isolated from hearts of 4-, 14- and 25-month-old F344 rats. Preparations were stimulated randomly at frequencies between 0 and 12 h. There were no age-associated differences in aiNa measured at any frequency or in the decay of Na+ activity following discontinuation of electrical stimulation. These data indicate that the aging-related decline in Na,K-ATPase does not result in elevated aiNa even at extremely high stimulation frequencies, thus suggesting that other routes of Na+ influx and efflux are also altered in atrial muscle.
Buscar no Google
Base de dados:
MEDLINE
Assunto principal:
Sódio
/
Envelhecimento
/
Miocárdio
Limite:
Animals
Idioma:
En
Ano de publicação:
1991
Tipo de documento:
Article