Relationship between nitrite / nitrate levels and antioxidant enzyme activities in type 2 diabetes mellitus

Abstract

Previously, it has been shown that poor glycaemic control is associated with increased free radical production leading to vascular complications and endothelium dependent relaxations are impaired. But it's not clear if there is any relation between Nitric Oxide (NO) and antioxidant enzyme activities in diabetes patients with vascular complications. The aim of this study was to investigate the antioxidant enzyme activities and nitrite/nitrate levels in type 2 diabetic patients and the relationship between oxidative stress and nitric oxide in patients with and without complication. Superoxide dismutase (SOD) and catalase activities and nitrite-nitrate levels were measured in patients with type 2 OM (n=40) and controls (n=20). While nitrite and nitrate levels of patients were lower (p<O,O5), catalase activities of patients were higher (p<O,O1) than controls. There was an insignificant depletion in (SOD) activity of patients. The presence of complication had no effect on these parameters. These findings support the previous data that show an elevation in free radical production. It's supposed that these free radicals may lead to an inhibition of nitric oxide activity through the various mechanism such as inhibition of nitric oxide synthase (ecNOS), impairment of signal transduction or peroxynitrite synthesis. We suggest that the nitrite-nitrate levels and superoxide dismutase activities can not be used as markers for the management of the complications of diabetes mellitus, but the importance of catalase activities are in discuss for next research.