Diabetes, Vol 29, Issue 3 213-216, Copyright © 1980 by American Diabetes Association
Inhibition of alloxan action in isolated pancreatic islets by superoxide dismutase, catalase, and a metal chelator
LJ Fischer and SA Hamburger
The possible participation of superoxide anions, hydrogen peroxide, and
hydroxyl radicals in the action of alloxan was investigated using isolated
rat pancreatic islets. Exposure of islets for 5 min to alloxan (0.15 or 0.2
mg/ml) inhibited subsequent glucose-stimulated insulin release. The
presence of superoxide dismutase (1000 U/ml), catalase (50 microgram/ml),
or a metal chelator diethylenetriaminepentacetic acid (1 mM) markedly
attenuated this effect of alloxan. Use of these agents afforded complete
protection from the lower concentration of alloxan and partial protection
from the higher concentration of the toxic compound. Inactivation of the
enzymes or addition of excess iron to the chelating agent before its use
with alloxan eliminated the protective action of these agents. The results
are consistent with the proposal that hydroxyl radicals, generated via
reactions that involve superoxide anions, hydrogen peroxide, and iron,
mediate the deleterious effect of alloxan in pancreatic islets.