Effects of extracellular sodium, quinidine, and ryanodine on slow response excitability in rabbit atrial trabeculae.
Braz J Med Biol Res
; 27(3): 755-66, 1994 Mar.
Article
em En
| MEDLINE
| ID: mdl-8081302
1. We investigated Na(+)-Ca2+ exchange and the involvement of the sarcoplasmic reticulum in frequency-dependent slow response excitability enhancement in rabbit atrial trabeculae. 2. Slow responses were induced in a modified Tyrode solution containing high K+ and Ba2+ and conventional electrophysiological techniques were used for stimulating and recording membrane potentials. 3. Under these conditions, the frequency-dependence of slow response excitability can be demonstrated with excitability enhancement as stimulation frequency is increased (0.25 to 1.0 Hz). 4. The frequency-dependent excitability enhancement depends on external Na+, increasing in high-[Na+]o (173.8 mM) and decreasing in low-[Na+]o (103.8 mM) media. 5. Quinidine (10 microM) and ryanodine (10 microM) decrease frequency-dependent slow response excitability enhancement. 6. These results indicate that the Na(+)-Ca2+ exchange might have an important role in frequency-dependent excitability enhancement of slow responses. Moreover, we suggest that the control of internal Ca2+ by the sarcoplasmic reticulum might have an additional role in regulating the excitability enhancement process in depolarized atrial trabeculae.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Sódio
/
Função Atrial
/
Espaço Extracelular
Limite:
Animals
Idioma:
En
Revista:
Braz J Med Biol Res
Ano de publicação:
1994
Tipo de documento:
Article
País de afiliação:
Brasil
País de publicação:
Brasil