ERYTHROCYTE CATALASE INACTIVATION (H2O2 PRODUCTION) BY ASCORBIC-ACID AND GLUCOSE IN THE PRESENCE OF AMINOTRIAZOLE - ROLE OF TRANSITION-METALS AND RELEVANCE TO DIABETES

Erythrocytes exposed to ascorbic acid in the presence of amino-triazol e undergo a dose- and time-dependent inactivation of endogenous catala se which is proportional to environmental (H2O2) concentrations. The p roduction of H2O2 seems to be dependent upon the availability of trans ition metal chelatable by o-phenanthroline (OPT), although the kinetic s of catalase inactivation and H2O2 production by externally added cop per ions in the presence of OPT is complex. Furthermore, although gluc ose is also able to undergo a transition-metal-catalysed oxidation yie lding H2O2, the production of H2O2 by glucose seems to be a minor proc ess by comparison with ascorbic acid oxidation. Indeed, on the basis o f these data, transition-metal-catalysed ascorbic acid oxidation is li kely to be a more important source of oxidative stress in the diabetic state than hyperglycaemia.