Ozagrel increases retinal arteriolar diameters in streptozotocin (STZ) ‐ induced diabetes

It has been reported that vasoconstriction occurs in the diabetic retina, although the mechanisms remain unknown. The objective of these experiments was to determine the role of thromboxane (TxA 2 ) in vasoconstriction at early time points in the diabetic retina. Male C57BL/6J mice were injected with STZ (200 mg/kg) at 12 weeks of age and remained diabetic 4 weeks. Age‐matched control mice were injected with vehicle alone. Upon visualization of the retina via intravital microscopy, the arterioles leading out of the optic disc were measured. Ozagrel (100 mg/kg), a TxA 2 synthase inhibitor, was infused at a rate of 20 μl/min, and arteriolar diameters were re‐measured 25 min following the start of infusion. Arteriolar diameters of diabetic mice before ozagrel were 13% smaller than in controls (p<0.0001), diameters after ozagrel were not different (2%, p=.57). Regression analysis showed a significant correlation between baseline diameter and percent change in diameter following ozagrel (p< 0.001, r 2 = 0.41), that is, the most constricted vessels responded most to the ozagrel. The results suggest a role for TxA 2 in the retinal arteriolar constriction induced by STZ. Supported by JDRF 1‐2003‐159.