Structural beta-cell changes and transient hyperglycemia in mice treated with compounds inducing inhibited citric acid cycle enzyme activity.

An initial transient hyperglycemia was seen in mice injected with asparagine, fluoroacetate, hydroxylamine, or malonate plus methionine, whereas an initial triphasic blood glucose response and a transient "secondary" hyperglycemia were exhibited in those injected with hydroxylamine plus arsenite, and a delayed hypoglycemia was observed in those treated with fluoroacetate or arsenite. The glucose-induced insulin secretion was significantly decreased in isolated pancreatic islets incubated with hydroxylamine plus arsenite. Light and electron microscopy, pyroantimonate technique, and X-ray microanalysis disclosed mitochondrial damage, degeneration, and necrosis among the beta-cells in the islets of mice injected with hydroxylamine plus arsenite. Glycogen depletion and microvesicular fatty change were seen in the liver of mice treated with fluoroacetate, arsenite, or hydroxylamine plus arsenite. These observations support the view that inhibition of the activity of citric acid cycle enzymes and associated reactions in the beta-cells play a role in the induction of diabetic features.