An oxidative mechanism is involved in high glucose-induced serum protein modification causing inhibition of...

In order to investigate the role of hyperglycemia on the development of atherosclerosis in diabetics, the effects of high glucose-induced modification of serum factors on the proliferation of bovine carotid artery endothelial cells were studied. Dialysates of high glucose-treated serum inhibit cell growth in a time- and glucose concentration-dependent manner. With 6 weeks of pretreatment, 16.7 mM glucose causes a 47.2% inhibition in cell growth compared to 5.6 mM glucose (P < 0.001). Pretreatment of serum in the presence of reduced glutathione (0.5-1.0 mM), an antioxidant, significantly prevents the high glucose-induced inhibition without inhibiting the formation of early non-enzymatic glycosylation products. Dithiothreitol (7.5 mM) treatment after preincubation with glucose fully restores the glucose-induced inhibition. When the dialysates are fractionated according to molecular mass, the high glucose-induced inhibition is maximal in the MW fraction above 100 kDa. These data suggest that high glucose conditions facilitate the susceptibility of serum proteins to sulfhydryl oxidation forming disulfide crosslinks and this oxidative process may contribute to the inhibition of endothelial cell proliferation.