G protein activation by uncaging of GTP-gamma-S in the leech giant glial cell.
J Exp Biol
; 210(Pt 21): 3771-9, 2007 Nov.
Article
en En
| MEDLINE
| ID: mdl-17951418
ABSTRACT
Glial cells can be activated by neurotransmitters via metabotropic, G protein-coupled receptors. We have studied the effects of 'global' G protein activation by GTP-gamma-S on the membrane potential, membrane conductance, intracellular Ca(2+) and Na(+) of the giant glial cell in isolated ganglia of the leech Hirudo medicinalis. Uncaging GTP-gamma-S (injected into a giant glial cell as caged compound) by moderate UV illumination hyperpolarized the membrane due to an increase in K+ conductance. Uncaging GTP-gamma-S also evoked rises in cytosolic Ca(2+) and Na+, both of which were suppressed after depleting the intracellular Ca(2+) stores with cyclopiazonic acid (20 micromol l(-1)). Uncaging inositol-trisphosphate evoked a transient rise in cytosolic Ca(2+) and Na+ but no change in membrane potential. Injection of the fast Ca(2+) chelator BAPTA or depletion of intracellular Ca(2+) stores did not suppress the membrane hyperpolarization induced by uncaging GTP-gamma-S. Our results suggest that global activation of G proteins in the leech giant glial cell results in a rise of Ca(2+)-independent membrane K+ conductance, a rise of cytosolic Ca(2+), due to release from intracellular stores, and a rise of cytosolic Na+, presumably due to increased Na+/Ca(2+) exchange.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Neuroglía
/
Guanosina 5'-O-(3-Tiotrifosfato)
/
Proteínas de Unión al GTP
/
Hirudo medicinalis
Límite:
Animals
Idioma:
En
Revista:
J Exp Biol
Año:
2007
Tipo del documento:
Article
País de afiliación:
Alemania