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A. S. Yadav; Tempol Improves Retinal Blood Flow in the Diabetic Mouse. Invest. Ophthalmol. Vis. Sci. 2010;51(13):5030.
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The aim of these experiments was to explore the role of superoxide in the early decrease of retinal blood flow in diabetic mice.
Diabetes was induced by streptozotocin, then 1 week later the C57BL6 mice were administered drinking water with (N=5) or without (N=6) the superoxide dismutase mimetic tempol (1 mM concentration) for the following 3 weeks. Non-diabetic age-matched mice (N=4) were included as controls. For each mouse, measurements of retinal vascular diameters and red blood cell (RBC) velocities were obtained via intravital microscopy for 3-5 feed arterioles (and venules) extending out of (and into) the optic disk, and the average blood flow in these vessels was calculated.
Arteriolar diameters (given in microns) averaged 57±3 (±SE) in controls, 53±1 in the untreated diabetics, and 60±3 in the tempol-treated diabetics. Venular diameters in these respective groups averaged 69±9, 60±6, and 61±5 microns. These differences did not quite reach statistical significance (p=0.14 for arterioles; p=0.10 for venules); however, statistical differences between groups were present for RBC velocities and blood flow rates. Average arteriolar velocities were significantly decreased in the untreated diabetics (68±6% of controls; p<0.01), but not in the tempol-treated diabetics (103±8% of controls). Similarly, venular velocities averaged 65±6% of controls (p<0.05) in untreated diabetics compared to 96±6% of controls with tempol. Finally, average vessel blood flow (arteriole and venules combined) decreased in the untreated diabetics to 55±6% of controls (p<0.01) compared to 93±11% of controls with tempol.
Administration of tempol in drinking water for the final 3 weeks of a 4-week streptozotocin protocol is able to attenuate the decrease in blood flow induced by diabetes, suggesting a possible role for superoxide.
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