Effects of oxygen-derived free radicals are suggested to be a potential pathogenic factor for endothelial dysfunction. In this study we sought to evaluate the effect of hydroxyl radicals on the human coronary vascular bed in type I diabetes mellitus using positron emission tomography (PET). Thirteen patients with type 1 diabetes underwent PET using nitrogen-13 ammonia at rest and during sympathetic stimulation with the cold pressor test (CPT). The rest-stress study protocol was repeated twice (on different days) using pre-stress infusion of either saline as placebo or deferoxamine, an iron chelator which inhibits generation of hydroxyl radicals. At rest, global MBF was higher in diabetics than in normal controls (78.1±17.5 vs 63.2±14.9 mg 100 g-1 min-1, P-1 min-1; saline, 75±19 ml 100 g-1 min-1, P=NS) or MVR (deferoxamine, 1.0±0.5 mmHg ml-1 100 g-1 min-1; saline, 1.2±0.6 mmHg ml-1 100 g-1 min-1, P=NS). In conclusion, inhibition of hydroxyl radical formation using deferoxamine significantly improved the responses of coronary microvasculature to sympathetic stimulation. Hydroxyl radicals may play a role in the pathogenesis of flow abnormalities in type 1 diabetes.
- Free radicals
- Positron emission tomography
- Type 1 diabetes mellitus
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging
- Radiological and Ultrasound Technology