Effect of NO synthase inhibition on retinal vessel reaction to isometric exercise in healthy humans

Acta Ophthalmologica
Michael LastaLeopold Schmetterer

Abstract

It has been shown that retinal blood flow is autoregulated, meaning that flow is independent of perfusion pressure within a certain range. We tested the hypothesis that nitric oxide (NO) synthase inhibition alters the response of retinal arterial and venous vessels during isometric exercise. In this study, nine healthy subjects were included. Each subject received the NO synthase inhibitor Ng-monomethyl-l-Arginine (l-NMMA, the α-receptor agonist phenylephrine or placebo intravenously on three study days. Retinal vessel diameter was assessed with the retinal vessel analyser (RVA), at baseline and during a squatting period of 6-7 min in absence or presence of l-NMMA, phenylephrine or placebo. Mean arterial pressure (MAP) and pulse rate (PR) increased significantly during all pretreatment squatting periods (p < 0.001) Retinal venous and arterial diameters showed a continuous decrease during squatting (p < 0.001). Phenylephrine increased MAP and PR but did not alter the retinal vessel diameter response to squatting. Administration of l-NMMA lead to a significant decrease in venous diameter before isometric exercise (p = 0.004). In addition, the retinal venous diameter response during administration of the NO synthase inhibitor was ...Continue Reading

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Citations

Apr 27, 2012·Thrombosis and Haemostasis·Rebekka Heitmar, Robert James Summers
Dec 1, 2015·Graefe's Archive for Clinical and Experimental Ophthalmology = Albrecht Von Graefes Archiv Für Klinische Und Experimentelle Ophthalmologie·Musa Yasin KayaToke Bek
Feb 15, 2013·Acta Ophthalmologica·Vincent DaienPierre Fesler
Jan 21, 2014·Diabetes Research and Clinical Practice·Ü KaracaC D A Stehouwer
Aug 7, 2012·Acta Ophthalmologica·Naim TeraiRichard Stodtmeister

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