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Journal of Diabetes Research
Volume 2017, Article ID 2309630, 6 pages
https://doi.org/10.1155/2017/2309630
Research Article

Dynamics of Insulin Secretion from EndoC-βH1 β-Cell Pseudoislets in Response to Glucose and Other Nutrient and Nonnutrient Secretagogues

Institute of Experimental Diabetes Research, Hannover Medical School, 30623 Hannover, Germany

Correspondence should be addressed to Sigurd Lenzen; ed.revonnah-hm@drugis.neznel

Received 8 May 2017; Revised 17 July 2017; Accepted 10 August 2017; Published 19 October 2017

Academic Editor: Andrea Tura

Copyright © 2017 Hiroki Teraoku and Sigurd Lenzen. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The dynamics of insulin secretion were characterized in response to a variety of physiological and pharmacological stimulators and other compounds in perifused pseudoislets generated from cells of the EndoC-βH1 β-cell line. Perifusion of EndoC-βH1 pseudoislets with the physiological stimulus glucose (16.7 mM) induced sustained insulin secretion, which was inhibited by mannoheptulose. The adenylate cyclase activators IBMX and forskolin strongly potentiated this secretion. Glibenclamide, a Kir 6.2 potassium channel blocker, and Bay K 8644, an opener of the voltage-sensitive Ca2+ channel, also potentiated glucose-induced insulin secretion. The dynamics of insulin secretion from EndoC-βH1 pseudoislets were characterized by an insulin secretory response to glucose starting within 1-2 min and passing over without interruption into a sustained phase of insulin release for the whole stimulation period. This lack of a transient decline between the first and the second phases of insulin release is an indication for a quick supply of insulin secretory granules from the reserve pool to the docking sites below the plasma membrane. Thereby, new secretory granules are directly made available for sustained exocytosis of insulin in EndoC-βH1 β-cells. The study shows that EndoC-βH1 β-cell pseudoislets are well suited for kinetic analyses of insulin secretion.