Investigation of the roles of Ca(2+) and InsP(3) diffusion in the coordination of Ca(2+) signals between connected hepatocytes.
J Cell Sci
; 114(Pt 11): 1999-2007, 2001 Jun.
Article
en En
| MEDLINE
| ID: mdl-11493636
ABSTRACT
Glycogenolytic agonists induce coordinated Ca(2+) oscillations in multicellular rat hepatocyte systems as well as in the intact liver. The coordination of intercellular Ca(2+) signals requires functional gap-junction coupling. The mechanisms ensuring this coordination are not precisely known. We investigated possible roles of Ca(2+) or inositol 1,4,5-trisphosphate (InsP(3)) as a coordinating messengers for Ca(2+) spiking among connected hepatocytes. Application of ionomycin or of supra-maximal concentrations of agonists show that Ca(2+) does not significantly diffuse between connected hepatocytes, although gap junctions ensure the passage of small signaling molecules, as demonstrated by FRAP experiments. By contrast, coordination of Ca(2+) spiking among connected hepatocytes can be favored by a rise in the level of InsP(3), via the increase of agonist concentrations, or by a shift in the affinity of InsP(3) receptor for InsP(3). In the same line, coordination cannot be achieved if the InsP(3) is rapidly metabolized by InsP(3)-phosphatase in one cell of the multiplet. These results demonstrate that even if small amounts of Ca(2+) diffuse across gap junctions, they most probably do not play a significant role in inducing a coordinated Ca(2+) signal among connected hepatocytes. By contrast, coordination of Ca(2+) oscillations is fully dependent on the diffusion of InsP(3) between neighboring cells.
Buscar en Google
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Inositol 1,4,5-Trifosfato
/
Calcio
/
Señalización del Calcio
/
Hepatocitos
Límite:
Animals
Idioma:
En
Revista:
J Cell Sci
Año:
2001
Tipo del documento:
Article
País de afiliación:
Francia
Pais de publicación:
ENGLAND
/
ESCOCIA
/
GB
/
GREAT BRITAIN
/
INGLATERRA
/
REINO UNIDO
/
SCOTLAND
/
UK
/
UNITED KINGDOM