Effect of caffeine on K+ efflux in frog skeletal muscle

The exposure of frog skeletal muscle to caffeine (3–4 mM) generates an increase of the K+ (42K+) efflux rate coefficient (k; K,o) which exhibits the following characteristics. First it is promoted by the rise in cytosolic Ca2+ ([Ca2+]i), because the effect is mimicked by ionomycin (1.25 µM), a Ca2+...

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Autores principales: Venosa, Roque Alberto, Hoya, Arturo
Formato: Articulo
Lenguaje:Inglés
Publicado: 1999
Materias:
Ciencias Médicas
Caffeine
Calcium
Efflux
Frog
Potassium
Skeletal muscle
Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/145104
Aporte de:
SEDICI (UNLP) de Universidad Nacional de La Plata
id I19-R120-10915-145104
record_format dspace
institution Universidad Nacional de La Plata
institution_str I-19
repository_str R-120
collection SEDICI (UNLP)
language Inglés
topic Ciencias Médicas
Caffeine
Calcium
Efflux
Frog
Potassium
Skeletal muscle
spellingShingle Ciencias Médicas
Caffeine
Calcium
Efflux
Frog
Potassium
Skeletal muscle
Venosa, Roque Alberto
Hoya, Arturo
Effect of caffeine on K+ efflux in frog skeletal muscle
topic_facet Ciencias Médicas
Caffeine
Calcium
Efflux
Frog
Potassium
Skeletal muscle
description The exposure of frog skeletal muscle to caffeine (3–4 mM) generates an increase of the K+ (42K+) efflux rate coefficient (k; K,o) which exhibits the following characteristics. First it is promoted by the rise in cytosolic Ca2+ ([Ca2+]i), because the effect is mimicked by ionomycin (1.25 µM), a Ca2+ ionophore. Second, the inhibition of caffeine-induced Ca2+ release from the sarcoplasmic reticulum (SR) by 40 µM tetracaine significantly reduced the increase in k; K,o (Δk; K,o). Third, charybdotoxin (23 nM), a blocker of the large-conductance Ca2+-dependent K+ channels (BKCa channels) reduced Δk; K,o by 22%. Fourth, apamin (10 nM), a blocker of the small-conductance Ca2+-dependent K+ channels (SKCa channels), did not affect Δk; K,o. Fifth, tolbutamide (800 µM), an inhibitor of KATP channels, reduced Δk; K,o by about 23%. Sixth, Ba2+, a blocker of most K+ channels, did not preclude the caffeine-induced Δk; K,o. Seventh, omitting Na+ from the external medium reduced Δk; K,o by about 40%. Eight, amiloride (5 mM) decreased Δk; K,o by 65%. It is concluded that the caffeine-induced rise of [Ca2+]i increases K+ efflux, through the activation of: (1) two channels (BKCa and KATP) and (2) an external Na+-dependent amiloride-sensitive process.
format Articulo
Articulo
author Venosa, Roque Alberto
Hoya, Arturo
author_facet Venosa, Roque Alberto
Hoya, Arturo
author_sort Venosa, Roque Alberto
title Effect of caffeine on K+ efflux in frog skeletal muscle
title_short Effect of caffeine on K+ efflux in frog skeletal muscle
title_full Effect of caffeine on K+ efflux in frog skeletal muscle
title_fullStr Effect of caffeine on K+ efflux in frog skeletal muscle
title_full_unstemmed Effect of caffeine on K+ efflux in frog skeletal muscle
title_sort effect of caffeine on k+ efflux in frog skeletal muscle
publishDate 1999
url http://sedici.unlp.edu.ar/handle/10915/145104
work_keys_str_mv AT venosaroquealberto effectofcaffeineonkeffluxinfrogskeletalmuscle
AT hoyaarturo effectofcaffeineonkeffluxinfrogskeletalmuscle
bdutipo_str Repositorios
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