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E. Mendrinos, I. K. Petropoulos, G. Mangioris, D. N. Papadopoulou, C. J. Pournaras; The Vasodilatory Effect of Intravitreal Juxta-Arteriolar Microinjection of L-Arginine in Acute Branch Retinal Vein Occlusion in Minipigs. Invest. Ophthalmol. Vis. Sci. 2009;50(13):76.
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© ARVO (1962-2015); The Authors (2016-present)
Branch retinal vein occlusion (BRVO) induces a decrease in the production of nitric oxide (NO) in the affected retina with resultant arteriolar vasoconstriction. The purpose of this study was to investigate the effect of L-Arginine, the substrate for NO production, on the retinal arteriolar diameter following acute BRVO in minipigs.
Under general anesthesia, 10 eyes of 10 minipigs were evaluated. Argon laser endo-photocoagulation was used for BRVO. Two hours after BRVO, an intravitreal juxta-arteriolar microinjection of 30 µl L-Arginine 1 mM (pH=7.4) was performed in 7 eyes. Three eyes received a microinjection of 30 µl of the solvent (pH=7.4) that was used to prepare the solution of L-Arginine and served as controls. The procedure was recorded in real time and retinal arteriolar diameter changes were measured in vivo using a Retinal Vessel Analyzer.
Overall (n=10), two hours after BRVO there was a 10.5 ± 1.9 % decrease in the retinal arteriolar diameter in the affected territories compared to baseline (p<0.05). An increase of 16.0 ± 3.0 % (p< 0.01) and 21.0 ± 7.0 % (p<0.05) of the arteriolar diameter was evidenced 10 and 15 minutes respectively after L-Arginine microinjection (n = 7) compared to the diameter prior to L-Arginine microinjection. Thereafter, the vasodilatory effect of L-Arginine started to decrease but persisted and remained significant at the end of the study period (5.0 ± 1.5 % at 30 min, p<0.05). Microinjection of the solvent that was used to prepare the solution of L-Arginine (n=3) did not produce any significant effect on the retinal arterioles, which remained constricted at all time-points (p>0.1).
We found a significant vasodilation after intravitreal juxta-arteriolar L-Arginine microinjection in eyes with experimental BRVO. L-Arginine microinjection can be a beneficial therapeutic option in acute BRVO, reversing the arteriolar vasoconstriction by stimulating NO production, thus leading to increase of the retinal arteriolar blood flow and possibly to improvement of the retinal cellular function in the occluded territory.
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