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GLYCINE TRANSFORMATION OF CA-2+ OSCILLATIONS INTO A SUSTAINED INCREASE PARALLELS POTENTIATION OF INSULIN RELEASE

Biomedical Sciences Research Institute Computer Science Research Institute Environmental Sciences Research Institute Nanotechnology & Advanced Materials Research Institute

TENGHOLM, A, McClenaghan, Neville, GRAPENGIESSER, E, GYLFE, E and HELLMAN, B (1992) GLYCINE TRANSFORMATION OF CA-2+ OSCILLATIONS INTO A SUSTAINED INCREASE PARALLELS POTENTIATION OF INSULIN RELEASE. BIOCHIMICA ET BIOPHYSICA ACTA, 1137 (3). pp. 243-247. [Journal article]

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Abstract

Increase of the glucose concentration from 3 to 11 mM resulted in a triphasic release of insulin from perifused ob/ob-mouse beta-cells. A slight inhibition was followed after 2 min by a marked peak and a less pronounced sustained response. At the lower glucose concentration glycine had only marginal effects. However, in the presence of 11 mM glucose, 1-10 mM glycine triggered an immediate and dose-dependent response with an initial peak of insulin release followed by sustained stimulation. In individual beta-cells, rise of the glucose concentration from 3 to 11 mM induced initial lowering of the cytoplasmic Ca2+ concentration ([Ca2+]i) followed by large amplitude oscillations from a level of 50-90 nM to peak values exceeding 300 nM. Already at a concentration of 1 mM, glycine transformed the oscillatory pattern into a sustained level with increase of time-average [Ca2+]i. This elevation became more pronounced in the presence of 10 mM glycine. The effects of glycine on insulin release and [Ca2+]i required extracellular Na+ and were reproduced with the N-methyl analogue sarcosine. It is suggested that glycine potentiation of secretion reflects the elevation of time-average [Ca2+]i both by increased entry and reduced elimination of the cation from the cytoplasm.

Item Type:Journal article
Faculties and Schools:Faculty of Life and Health Sciences
Faculty of Life and Health Sciences > School of Biomedical Sciences
Research Institutes and Groups:Biomedical Sciences Research Institute
Biomedical Sciences Research Institute > Diabetes
ID Code:14183
Deposited By:Mrs Caroline Adams
Deposited On:11 Jun 2010 09:36
Last Modified:15 Jun 2011 11:10

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