Intravenou Adminitration of L-Arginine Increae Retinal and Choroidal Blood Flow

Purpoe Nitric oxide (NO) i among the mot important regulator of ocular perfuion. L-arginine, an amino acid, i the precuror of NO ynthei. The aim of the preent tudy wa to determine whether adminitration of L-arginine affect ocular blood flow. Deign L-arginine (1 g/min) or placebo wa adminitered intravenouly for 30 minute in 12 healthy volunteer in a randomized, double-maked, two-way cro-over deign. Method Ocular hemodynamic were meaured before, in the lat 10 minute of the infuion period, a well a 30 minute after ceation of the adminitration. Retinal veel diameter were meaured with a retinal veel analyzer, red blood cell velocitie with bidirectional laer Doppler velocimetry, and pulatile choroidal blood flow wa meaured uing laer interferometry. Reult L-arginine ignificantly decreaed mean arterial preure by −8 ± 5% and −6 ± 7% at the two time point (P < .01), repectively. Intravenou adminitration of L-arginine increaed choroidal blood flow by +10 ± 6% and +12 ± 7%, repectively. Retinal venou diameter decreaed by −2.5 ± 2.1% and −1.4 ± 2.7%, repectively, wherea red blood cell velocity ignificantly increaed after adminitration of L-arginine by +22 ± 23% and +20 ± 19% at the two time point. Thu, calculated blood flow in retinal vein, increaed by +21 ± 18% and +21 ± 19% before and after the end of L-arginine infuion. Concluion Intravenou adminitration of L-arginine increae retinal and choroidal blood flow in healthy volunteer. Whether thi effect i related to an increaed NO-production or an unidentified mechanim remain to be clarified. However, adminitration of L-arginine might be an intereting new approach to therapeutically increae ocular blood flow in ocular vacular dieae.