Pancreatic islet cells: a model for calcium-dependent peptide release

9 páginas, 4 figuras.-- et al.
In mammals the concentration of blood glucose is kept close to 5 mmol/l. Different cell types in the islet of Langerhans participate in the control of glucose homeostasis. β-cells, the most frequent type in pancreatic islets, are responsible for the synthesis, storage, and release of insulin. Insulin, released with increases in blood glucose promotes glucose uptake into the cells. In response to glucose changes, pancreatic α-, β-, and δ-cells regulate their electrical activity and Ca2+ signals to release glucagon, insulin, and somatostatin, respectively. While all these signaling steps are stimulated in hypoglycemic conditions in α-cells, the activation of these events require higher glucose concentrations in β and also in δ-cells. The stimulus-secretion coupling process and intracellular Ca2+ ([Ca2+]i) dynamics that allow β-cells to secrete is well-accepted. Conversely, the mechanisms that regulate α- and δ-cell secretion are still under study. Here, we will consider the glucose-induced signaling mechanisms in each cell type and the mathematical models that explain Ca2+ dynamics.
The authors are supported by the Fundación Progreso y Salud, Consejería de Salud, Junta de Andalucía (Grant No. PI-0022/2008), the Spanish Ministry of Science and Innovation (Grant Nos. BFU2007-67607 and BFU2008-01492), and the Red TERCEL (Grant No. RD06/0010/0025). CIBERDEM is an initiative of Instituto de Salud Carlos III.