@article{10902/3752,
year = {2012},
url = {http://hdl.handle.net/10902/3752},
abstract = {Glucagon hormone is synthesized and released by pancreatic α-cells, one of the islet-cell types. This hormone, along with insulin, maintains blood glucose levels within the physiological range. Glucose stimulates glucagon release at low concentrations (hypoglycemia). However, the mechanisms involved in this secretion are still not completely clear. Here, using experimental calcium time series obtained in mouse pancreatic islets at low and high glucose conditions, we propose a glucagon secretion model for α-cells. Our model takes into account that the resupply of releasable granules is not only controlled by cytoplasmic Ca²+, as in other neuroendocrine and endocrine cells, but also by the level of extracellular glucose. We found that, although calcium oscillations are highly variable, the average secretion rates predicted by the model fall into the range of values reported in the literature, for both stimulated and non-stimulated conditions. For low glucose levels, the model predicts that there would be a well-controlled number of releasable granules refilled slowly from a large reserve pool, probably to ensure a secretion rate that could last for several minutes. Studying the α-cell response to the addition of insulin at low glucose, we observe that the presence of insulin reduces glucagon release by decreasing the islet Ca²+ level. This observation is in line with previous work reporting that Ca²+ dynamics, mainly frequency, is altered by insulin. Thus, the present results emphasize the main role played by Ca²+ and glucose in the control of glucagon secretion by α-cells. Our modeling approach also shows that calcium oscillations potentiate glucagon secretion as compared to constant levels of this cellular messenger. Altogether, the model sheds new light on the subcellular mechanisms involved in α-cell exocytosis, and provides a quantitative predictive tool for studying glucagon secretion modulators in physiological and pathological conditions.},
organization = {This work was supported by i-MATH Future Platform, Project Number C3-0136 (www.i-math.org), Ministerio de Ciencia e Innovación, Spanish Government, Project BFU2010-21773 (www.micinn.es), CONACyT-Mexico, PhD scholarship number 67287 (www.conacyt.mx), ESF FUNCDYN Programme, Exchange Grants EX/2337 and EX/3617 (www.esf.org), and Fonds National de la Recherche Médicale, grant 3.4636.04 (www2.frs.fnrs.be). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.},
publisher = {PLOS Public Library of Science},
publisher = {PLoS ONE, 2012, 7(3), e32282},
title = {Model for glucagon secretion by pancreatic α-cells},
author = {González Vélez, Virginia and Dupont, Geneviève and Gil Gómez, Amparo and González Álvarez, Alejandro and Quesada Moll, Iván},
}