Homocystein levels and erythrocyte glutathione S-transferase activity in hemodialysis population

Aim of the study was to evaluate the relationship between total plasma Hcy and e-GST activity in 62 ESRD patients on MHD and in 57healthy controls. Results :Over-activity of GST was detected in the erythrocytes of uremic patients. Both mean e-GST activity and mean plasma Hcy levels were increased in HD patients compared to controls (10,47±2,86U/grHbversus5.63±1.7U/grHb,p<0.0001;52.42±28.63μmoli/Lversus13.65±6.13μmoli/L,p<0.0001). Furthermore, a significant direct correlation was found between plasma Hcy levels and e-GST activity (r=0.79,p<0.0001). Conclusions: GST may be considered a marker of uremic toxicity. The molecular mechanisms responsible for the reduced bioavailability of endothelium-derived nitric oxide (NO) induced by Hcy may involve an increase of oxidative stress at the vascular level and an important inhibition of the enzymatic antioxidant capacity. Since it was observed that the glutathione peroxidise (GPx) activity is inhibited by high plasma concentration of Hcy, the increased e-GST activity may be due to an enhanced oxidative stress always observed in HD patients and in particular under severe hyper-homocysteinemia conditions.