Activation of a novel non‐selective cation channel by alloxan and H2O2 in the rat insulin‐secreting cell line CRI‐G1

Abstract

1 Alloxan and its auto‐oxidation product hydrogen peroxide (H₂O₂) irreversibly depolarize insulinoma cells by opening a non‐selective cation channel. The channel opened is characterized by a linear current–voltage relation with a conductance of approximately 70 pS and very slow kinetics (of the order of seconds). 2 Cells are protected against the alloxan‐induced channel opening and consequent cell depolarization by the presence of H₂O₂ and hydroxyl radical scavengers. 3 The free radical‐activated non‐selective cation channel is not operative in isolated patches but can be activated by the application of β‐NAD to the cytoplasmic aspect of the membrane.