FIG. 4.

Total superoxide generation in retinal tissue. Superoxide anion generation of retinal tissue was determined by the lucigenin-enhanced chemiluminescence method, and photoemission was measured every 10 s for 3 min. The peak level of superoxide generation was observed ∼3 min after lucigenin was added to the reaction buffer containing retina from different groups. Diabetes increased superoxide production (RLU · min⁻¹ · mg protein⁻¹) in the retina, and the concomitance of diabetes and hypertension further exacerbated this parameter. The presence of diphenyliodonium (20 μmol/l), an inhibitor of flavin-containing oxidases, did not affect superoxide production, whereas preincubation with rotenone (100 μmol/l) resulted in a marked reduction in superoxide production from retinal tissue. This indicates that mitochondria are an important source of the superoxide in retina tissue. Treatment with the ABR losartan reduced superoxide production to levels observed in the control groups. Bars are the means ± SD. *P = 0.03 vs. control WKY; †P = 0.0002 vs. other groups. CT, control; DM, diabetic; DPI, diphenyliodonium.