Effects of morphological and functional heterogeneities on the intracellular Ca2+ signals in coupled pancreatic beta cells

Gerardo Jorge Felix-Martinez*, I. Morales-Reyes, J. R. Godinez-Fernandez

Abstract


The Islets of Langerhans are mainly composed of insulin-secreting pancreatic β-cells, glucagon-secreting α-cells and somatostatin-secreting δ-cells[1]. At the cellular level, secretion of these hormones takes place through a common mech- anism involving glucose metabolism, electrical activity and Ca2+-handling[2]. In addition, pancreatic hormone secretion is regulated by intra-islet interactions including paracrine and autocrine signals, as well as electrical coupling mediated by gap junctions between β-cells[3].

Electrical coupling between β-cells has been previously studied both theo- retically and experimentally. In these studies, it was shown that β-cell coupling is essential for the synchronized release of insulin[1]. In addition, it was demon- strated that the lack of functional gap junctions leads to impaired pulsatile insulin secretion due to uncoordinated Ca2+ oscillations[4].

In this work we used a computational model to assess the effect of morpho- logical and functional heterogeneities in the islet β-cells (including differences in cell sizes, β-cell interconnectivity and electrophysiological and Ca2+ buffering properties) on the Ca2+ signal produced in the cytosol, ultimately related to the secretory response of the islet β-cells.


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References


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