Protective mechanism of glucose against alloxan-induced pancreatic β-cell damage

Glucose prevented the alloxan- or H₂O₂-induced inhibition of insulin secretion in rat pancreatic islets. Hydrogen peroxide was detected during the incubation of islets with alloxan, and this generation of hydrogen peroxide was not affected by glucose. Treatment of β-cells with alloxan or H₂O₂ caused elevation of cytosolic free Ca²⁺ and decrease of cellular NAD⁺. Glucose blocked the decrease of cellular NAD⁺ level, but did not abolish the increase of cytosolic Ca²⁺. These results indicate that glucose protected pancreatic β-cell damage after the H₂O₂ generation and Ca²⁺ influx on a chain of reactions in the diabetogenesis of alloxan.