Mechanism of activation of the Ca(2+)-activated K+ channel by cyclic AMP in cultured porcine coronary artery smooth muscle cells.
Life Sci
; 53(14): 1129-35, 1993.
Article
em En
| MEDLINE
| ID: mdl-8396704
ABSTRACT
Activation of the Ca(2+)-activated K+ channel (KCa-channel) by adenosine 3', 5'-cyclic monophosphate (cAMP) and cAMP-dependent protein kinase (A-kinase) in cultured smooth muscle cells from porcine coronary artery was investigated using the patch-clamp technique. In cell-attached patches, the KCa-channel was activated when forskolin (10 microM) was applied to the bath. In excised inside-out patches, application of 50 microM cAMP to the bath activated the KCa-channel in the presence of A-kinase (10 units/ml) and ATP (1 mM). In addition, the KCa-channel was activated directly by application of cAMP to the cytoplasmic side of the membrane in the absence of A-kinase. The activation by cAMP or by A-kinase required intracellular Ca2+, and was enhanced by increase of intracellular Ca2+. At a low concentration (3 x 10(-7) M) of Ca2+, more than 2 mM cAMP was required for activation of the KCa-channel, but with 10(-6) M Ca2+, 100 microM cAMP was sufficient for activation. These results suggest that there are two mechanisms of activation of the KCa-channel by cAMP direct activation, and indirect activation via phosphorylation of the channel by A-kinase.
Buscar no Google
Base de dados:
MEDLINE
Assunto principal:
Canais de Potássio
/
Cálcio
/
AMP Cíclico
/
Músculo Liso Vascular
Idioma:
En
Ano de publicação:
1993
Tipo de documento:
Article