Alloxan-glucose interaction: Effect on incorporation of¹⁴C-leucine into pancreatic islets of rat

The acute effect of alloxan on the incorporation of¹⁴C-leucine into isolated rat islets of Langerhans was studied. I.v. administration of alloxan (40 mg/kg body weight) in rats inhibited the subsequent in vitro incorporation of¹⁴C-leucine into (pro-)insulin in the isolated islets. Glucose (750 mg/kg body weight), when administered 5 min prior to alloxan, completely protected the islets against alloxan toxicity. The protective effect of glucose was partly reversed when the concentration of alloxan was raised to 80 mg/kg body weight. Similar results of inhibition of (pro-)insulin biosynthesis by alloxan and its protection by glucose were obtained when isolated rat islets were exposed to alloxan and/or glucose in vitro. Islets exposed to glucose in vitro immediately after alloxan exposure showed a slower rate of inhibition of (pro-)insulin biosynthesis, as compared to islets washed before exposure to D-glucose. In view of these findings, it is suggested that there is a common recognition site on B-cell for alloxan and glucose.