Glucose increases extracellular [Ca2+] in rat insulinoma (INS-1E) pseudoislets as measured with Ca2+-sensitive microelectrodes

Cell Calcium
Andrea GerbinoMatilde Colella

Abstract

Secretory granules of pancreatic β-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 β-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) β-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, o...Continue Reading

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Citations

Mar 28, 2018·International Journal of Molecular Sciences·Andrea Gerbino, Matilde Colella
Nov 3, 2016·F1000Research·Matilde ColellaSilvana Curci
Aug 16, 2013·The Journal of Biological Chemistry·Teresa Anna GiancasperoMaria Barile
Jul 4, 2013·Molecular Endocrinology·Eric M WausonMelanie H Cobb
Apr 13, 2018·International Journal of Molecular Sciences·Andrea GerbinoMonica Carmosino

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