Glucose increases extracellular [Ca2+] in rat insulinoma (INS-1E) pseudoislets as measured with Ca2+-sensitive microelectrodes.
Cell Calcium
; 51(5): 393-401, 2012 May.
Article
em En
| MEDLINE
| ID: mdl-22361140
Secretory granules of pancreatic ß-cells contain high concentrations of Ca2+ ions that are co-released with insulin in the extracellular milieu upon activation of exocytosis. As a consequence, an increase in the extracellular Ca2+ concentration ([Ca2+]ext) in the microenvironment immediately surrounding ß-cells should be expected following the exocytotic event. Using Ca2+-selective microelectrodes we show here that both high glucose and non-nutrient insulinotropic agents elicit a reversible increase of [Ca2+]ext within rat insulinoma (INS-1E) ß-cells pseudoislets. The glucose-induced increases in [Ca2+]ext are blocked by pretreatment with different Ca2+ channel blockers. Physiological agonists acting as positive or negative modulators of the insulin secretion and drugs known to intersect the secretory machinery at different levels also induce [Ca2+]ext changes as predicted on the basis of their described action on insulin secretion. Finally, the glucose-induced [Ca2+]ext increase is strongly inhibited after disruption of the actin web, indicating that the dynamic [Ca2+]ext changes recorded in INS-1E pseudoislets by Ca2+-selective microelectrodes occur mainly as a consequence of exocytosis of Ca2+-rich granules. In conclusion, our data directly demonstrate that the extracellular spaces surrounding ß-cells constitute a restricted domain where Ca2+ is co-released during insulin exocytosis, creating the basis for an autocrine/paracrine cell-to-cell communication system via extracellular Ca2+ sensors.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Cálcio
/
Sinalização do Cálcio
/
Glucose
/
Insulina
Tipo de estudo:
Diagnostic_studies
/
Prognostic_studies
Limite:
Animals
Idioma:
En
Ano de publicação:
2012
Tipo de documento:
Article