Ca2+ entry, efflux and release in smooth muscle
Biol. Res
;
37(4): 617-624, 2004. graf
Artigo
em Inglês
| LILACS
| ID: lil-437517
ABSTRACT
Control of smooth muscle is vital for health. The major route to contraction is a rise in intracellular [Ca2+], determined by the entry and efflux of Ca2+ and release and re-uptake into the sarcoplasmic reticulum (SR). We review these processes in myometrium, to better understand excitation-contraction coupling and develop strategies for preventing problematic labours. The main mechanism of elevating [Ca2+] is voltage-gated L-type channels, due to pacemaker activity, which can be modulated by agonists. The rise of [Ca2+] produces Ca-calmodulin and activates MLCK. This phosphorylates myosin and force results. Without Ca2+ entry uterine contraction fails. The Na/Ca exchanger (NCX) and plasma membrane Ca-ATPase (PMCA) remove Ca2+, with contributions of 30 percet and 70 percet respectively. Studies with PMCA-4 knockout mice show that it contributes to reducing [Ca2+] and relaxation. The SR contributes to relaxation by vectorially releasing Ca2+ to the efflux pathways, and thereby increasing their rates. Agonists binding produces IP3 which can release Ca from the SR but inhibition of SR Ca2+ release increases contractions and Ca2+ transients. It is suggested that SR Ca2+ targets K+ channels on the surface membrane and thereby feedback to inhibit excitability and contraction.
Texto completo:
DisponíveL
Índice:
LILACS (Américas)
Assunto principal:
Retículo Sarcoplasmático
/
Contração Uterina
/
Cálcio
/
Miométrio
Limite:
Animais
Idioma:
Inglês
Revista:
Biol. Res
Assunto da revista:
Biologia
Ano de publicação:
2004
Tipo de documento:
Artigo
País de afiliação:
Reino Unido
Instituição/País de afiliação:
The University of Liverpool/GB
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