Frequency-dependent excitability enhancement in isolated ventricular myocardial cells
Braz. j. med. biol. res
; 24(11): 1179-83, 1991. ilus, tab
Artigo
em Inglês
| LILACS
| ID: lil-105501
Biblioteca responsável:
BR1.1
RESUMO
The understanding of the mechanisms underling the frquency-dependent slow response ecitability enhancement has been hndered by the problem inhyerent in multicellular preparations. These include ion acdcumulation/depletion in intercellular space and difficulties in the spatial control of transmembrane voltage. In the present communication we show that isolated ventricular cells exposed to a depolarizing (high potassium-barium containing) solution present electrophysiological properties similar to those of mulcellular preparations stable resting potential of -45.2 ñ 0.7 mV (mean ñ SEM, N = 57) in 75% of the cells and spontaneous activity in the remaining 25% (maximum diatolic potential of -41.9 ñ 1.2 mV, N=19)ñ high input resistance and slow response, under current clamp conditions. Under whole cell voltage clamp conditions with -45 mV holding potential, transient outward and delayed potassium currents as well as typical L type calcium channel are present. These cells also present thye frequency-dependent excitability enhancement of the slow response, with the threshold stimulus at 1 Hz corresponding to about 50% of that obtained at 0.1 Hz. Thus, isolated ventricular cells constitute a suitable model for the study of frequency-dependent exitability enhancement of the slow response
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Base de dados:
LILACS
Assunto principal:
Espaço Extracelular
/
Ventrículos do Coração
Tipo de estudo:
Estudo prognóstico
Limite:
Animais
Idioma:
Inglês
Revista:
Braz. j. med. biol. res
Assunto da revista:
Biologia
/
Medicina
Ano de publicação:
1991
Tipo de documento:
Artigo
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Congresso e conferência