Miwa I, Taniguchi S
Department of Pathobiochemistry, Faculty of Pharmacy, Meijo University, Nagoya, Japan.
Horm Metab Res. 2002 Aug;34(8):450-4. doi: 10.1055/s-2002-33594.
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 microM 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.
果糖增强葡萄糖诱导的胰岛素分泌的机制尚不清楚。本研究旨在探讨这种己酮糖是否增强葡萄糖诱导的胰岛素分泌的ATP敏感性钾通道非依赖性途径，以及如果是这样，这是如何发生的。当在150微摩尔二氮嗪（一种ATP敏感性钾通道开放剂）存在的情况下，将分离的大鼠胰岛与50毫摩尔氯化钾一起孵育使其去极化时，10毫摩尔葡萄糖加20毫摩尔果糖引起的胰岛素分泌明显高于单独使用10毫摩尔葡萄糖，而单独使用20毫摩尔果糖则不刺激胰岛素分泌。与单独用葡萄糖孵育的胰岛相比，用葡萄糖加果糖孵育的胰岛中1,6-二磷酸果糖和三磷酸肌醇含量明显更高。结果表明，果糖有能力增强葡萄糖诱导的胰岛素分泌的ATP敏感性钾通道非依赖性途径。果糖与葡萄糖共同存在诱导的1,6-二磷酸果糖含量增加，导致三磷酸肌醇含量升高，这可能是果糖增强葡萄糖诱导的胰岛素分泌所涉及的信号之一。
