Interaction of Alloxan and Anomers of D-Glucose on Glucose-induced Insulin Secretion and Biosynthesis in Vitro

  1. Boniface J Lin, M.D.
  1. Department of Medicine Aichigakuin University, Nagoya, Japan Department of Clinical Biochemistry, Meijo University Nagoya, Japan Department of Physiology, University of Toronto Toronto, Canada
  1. Address reprint requests to A. Niki, M.D., Department of Medicine, Aichigakuin University, 2-11 Suemori-dori, Chikusaku, Nagoya, 464 Japan.

Abstract

The direct effects of alloxan on glucose-induced insulin secretion and biosynthesis and the interaction of alloxan and D-glucose anomers were studied in vitro by use of isolated islets from rat pancreas. Islets were pretreated by incubation for five minutes in media containing alloxan (0.2 mg./ml.) alone or alloxan with either the α or β anomer of D-glucose (3 mg./ml.). After washing, batches of five islets were incubated in the medium supplemented with glucose (1.8 mg./ml.) for 60 minutes to observe insulin secretion and for 90 minutes to observe insulin biosynthesis. Prior exposure to alloxan alone produced marked inhibition of subsequent glucose-induced insulin secretion and biosynthesis. A significantly greater protection against these inhibitory effects of alloxan was observed by using the α anomer of D-glucose than the β anomer. The anomeric preference of D-glucose for protecting islet cells from the inhibitory effect of alloxan on glucose-induced insulin secretion and biosynthesis was similar to that for triggering insulin secretion. Possible mechanisms of the inhibitory effect of alloxan and the protective effect of D-glucose anomers in connection with those of other sugars are discussed. It is suggested that a glucoreceptor, stereospecific to the α anomer of D-glucose, may exist for both insulin secretion and biosynthesis.

  • Accepted March 10, 1976.
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