A comparison of the effects of UTP and ATP on the Ca2 release channel of skeletal muscle sarcoplasmic reticulum
Braz. j. med. biol. res
; 27(11): 2661-6, Nov. 1994. ilus, tab
Article
em En
| LILACS
| ID: lil-153989
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BR1.1
RESUMO
Heavy sarcoplasmic reticulum (SR) membrane fractions from rabbit and porcine skeletal muscle were incorporated into planar lipid bilayers and the activity of the Ca2+ release channels was recorded under voltage clamp, using Cs+ as the current carrier. The effects of the nucleotides adenosine triphosphate (ATP) and uridine triphosphate (UTP) on channel activity were studied at a holding potential of +30 mV. UTP (0.1-1.0 mM) had no effect per se on the conductance or the gating properties of the Ca2+ release channels. In contrast, ATP (>0.1 mM) increased Po, the open channel probability, and both to1 and to2, the open time constants, and decreased tc1 and tc2, the closed time constants. The Ca2+ channel conductance, however, was not affected by ATP. Ruthenium red (1-2 µM), a well-known inhibitor of the SR Ca2+ release channel, abolished the ATP-induced channel activation. These electrophysiological data provide support for our contention (G. Suarez-Kurtz et al (1993). Anais da Academia Brasileira de Ciências, 65 330) taht the UTP-induced tension in mammalian "skinned" mmuscle fibers is not due to stimulated release of SR-stored Ca2+ via the release channel
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Índice:
LILACS
Assunto principal:
Uridina Trifosfato
/
Canais de Cálcio
Limite:
Animals
Idioma:
En
Revista:
Braz. j. med. biol. res
Assunto da revista:
BIOLOGIA
/
MEDICINA
Ano de publicação:
1994
Tipo de documento:
Article
/
Congress and conference