Protein kinase C inhibition of cloned inward rectifier (HRK1/KIR2.3) K+ channels expressed in Xenopus oocytes.
J Physiol
; 495 ( Pt 3): 681-8, 1996 Sep 15.
Article
em En
| MEDLINE
| ID: mdl-8887775
ABSTRACT
1. The effect of protein kinase activators on cloned inward rectifier channels expressed in Xenopus oocytes was examined using a two-electrode voltage clamp. PKA activators caused no change in KIR1.1, KIR2.1, or KIR2.3 current. The PKC activators phorbol 12-myristate 14-acetate (PMA) and phorbol 12, 13-dibutyrate (PDBu) inhibited KIR2.3 currents, but not KIR2.1 or KIR1.1 current. This inhibition was blocked by staurosporine. An inactive phorbol ester, 4 alpha-phorbol 12, 13-didecanoate (4 alpha-PDD), had no effect on KIR2.3. 2. Upon changing solution from 2 to 98 microM K+, KIR2.3 but not KIR1.1 or KIR2.1 currents typically 'ran down' over 5 min to 60-80% of maximum amplitude. Rundown occurred even if PMA was applied before changing to high [K+] solution, indicating that rundown was independent of PKC activity. Rundown was evoked by substituting NMG+ for Na+, showing that it results from low [Na+] and not from high [K+]. 3. These results suggest that KIR2.3, but not KIR1.1 or KIR2.1, is subject to regulation, both by PKC activation and as a consequence of low [Na+]o. The difference in secondary regulation may account for specific responses to PKC stimulation of tissues expressing otherwise nearly identical KIR channels.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Proteína Quinase C
/
Canais de Potássio Corretores do Fluxo de Internalização
/
Bloqueadores dos Canais de Potássio
Limite:
Animals
Idioma:
En
Revista:
J Physiol
Ano de publicação:
1996
Tipo de documento:
Article
País de afiliação:
Estados Unidos