Vascular smooth muscle cell hypertrophy induced by glycosylated human oxyhaemoglobin

1 Nonenzymatic protein glycosylation is a possible mechanism contributing to oxidative stress and vascular disease in diabetes. In this work, the influence of 14%‐glycosylated human oxyhaemoglobin (GHHb), compared to the non‐glycosylated protein (HHb), was studied on several growth parameters of rat cultured vascular smooth muscle cells (VSMC). A role for reactive oxygen species was also analysed. 2 Treatment of VSMC for 48 h with GHHb, but not with HHb, increased planar cell surface area in a concentration dependent manner. The threshold concentration was 10 n M , which increased cell size from 7965±176 to 9411±392 μm 2 . Similarly, only GHHb enhanced protein content per well in VSMC cultures. 3 The planar surface area increase induced by 10 n M GHHb was abolished by superoxide dismutase (SOD; 50–200 u ml −1 ), deferoxamine (100 n M –100 μ M ), or dimethylthiourea (1 m M ), while catalase (50–200 u ml −1 ) or mannitol (1 m M ) resulted in a partial inhibition of cell size enhancement. 4 When a known source of oxygen free radicals was administered to VSMC, the xanthine/xanthine oxidase system, the results were analogous to those produced by GHHb. Indeed, enhancements of cell size were observed, which were inhibited by SOD, deferoxamine, or catalase. 5 These results indicate that, at low concentrations, GHHb induces hypertrophy in VSMC, this effect being mediated by superoxide anions, hydrogen peroxide, and/or hydroxyl radicals. Therefore, glycosylated proteins can have a role in the development of the structural vascular alterations associated to diabetes by enhancing oxidative stress.British Journal of Pharmacology (1998) 125 , 637–644; doi: 10.1038/sj.bjp.0702097