Capillary electrophoretic assay for nitrate levels in the vitreous of proliferative diabetic retinopathy

The determination of nitric oxide (NO) in human vitreous samples is complicated by the relatively short half-life of the analyte and the viscous, high salt and protein biological matrix. In this work, we developed a fast (<5 min) and useful CE method to determine the stable metabolite, nitrate, from vitreous samples. This proposed method has been successfully applied to determine the nitrate levels from the vitreous humor of patients undergoing vitrectomy for a variety of conditions. A statistically significant increase (P = 0.000001) of the mean level of nitrate was observed in vitreous humor of patients with proliferative diabetic retinopathy (41.17 ± 4.09 μM, n = 27) versus controls (15.22 ± 0.86 μM, n = 35). The elevated levels of nitrate in the vitreous of patients known to have diabetic retinopathy suggests that NO is involved with the pathology of this disease.