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DOI: 10.1055/s-2002-33594
© Georg Thieme Verlag Stuttgart · New York
Acceleration by Fructose of the ATP-Sensitive K+ Channel-Independent Pathway of Glucose-Induced Insulin Secretion
Publication History
Received: 3 January 2002
Accepted after revision: 13 March 2002
Publication Date:
25 September 2002 (online)
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Abstract
The mechanism with which fructose augments glucose-induced insulin secretion is still unclear. The present study was aimed at examining whether the ketohexose potentiates the ATP-sensitive K+ channel-independent pathway of glucose-induced insulin secretion and, if so, how this happens. When isolated rat islets were depolarized by incubating them with 50 mM KCl in the presence of 150 µM diazoxide (an opener of ATP-sensitive K+ channels), 10 mM glucose plus 20 mM fructose elicited significantly higher insulin secretion than 10 mM glucose alone, whereas 20 mM fructose alone did not stimulate insulin secretion. The fructose 1,6-bisphosphate and inositol trisphosphate contents were markedly higher in islets incubated with glucose plus fructose than in islets incubated with glucose alone. The results demonstrate that fructose has the ability to potentiate the ATP-sensitive K+ channel-independent pathway of glucose-induced insulin secretion. The increase in fructose 1,6-bisphosphate content induced by the co-presence of fructose with glucose, resulting in the rise in inositol trisphosphate content, is likely to be one of the signals involved in the fructose potentiation of glucose-induced insulin secretion.
Key words
Insulin Secretion - Fructose - Glycolytic Intermediate - Inositol Trisphosphate - Diazoxide
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I. Miwa
Department of Pathobiochemistry · Faculty of Pharmacy · Meijo University
Tempaku-ku · Nagoya 468-8503 · Japan
Phone: + 81 (52) 832 17 81
Fax: + 81 (52) 834 87 80
Email: miwaichi@ccmfs.meijo-u.ac.jp