Author:
Dorner Guido T.,Garhofer Gerhard,Kiss Barbara,Polska Elzbieta,Polak Kaija,Riva Charles E.,Schmetterer Leopold
Abstract
The purpose of the present study was to investigate the contribution of basal nitric oxide (NO) on retinal vascular tone in humans. In addition, we set out to elucidate the role of NO in flicker-induced retinal vasodilation in humans. Twelve healthy young subjects were studied in a three-way crossover design. Subjects received an intravenous infusion of either placebo or NG-monomethyl-l-arginine (l-NMMA; 3 or 6 mg/kg over 5 min), an inhibitor of NO synthase. Thereafter, diffuse luminance flicker was consecutively performed for 16, 32, and 64 s at a frequency of 8 Hz. The effect of l-NMMA on retinal arterial and venous diameter was assessed under resting conditions and during the hyperemic flicker response. Retinal vessel diameter was measured with a Zeiss retinal vessel analyzer. l-NMMA significantly reduced arterial diameter (3 mg/kg: –2%; 6 mg/kg: –4%, P < 0.001) and venous diameter (3 mg/kg: –5%; 6 mg/kg: –8%, P < 0.001). After placebo infusion, flicker induced a significant increase in retinal vessel diameter ( P < 0.001). At a flicker duration of 64 s, arterial diameter increased by 4% and venous diameter increased by 3%. l-NMMA did not abolish these hyperemic responses but blunted venous vasodilation ( P = 0.017) and arterial vasodilation ( P = 0.02) in response to flicker stimulation. Our data indicate that NO contributes to basal retinal vascular tone in humans. In addition, NO appears to play a role in flicker-induced vasodilation of the human retinal vasculature.
Publisher
American Physiological Society
Subject
Physiology (medical),Cardiology and Cardiovascular Medicine,Physiology
Reference51 articles.
1. Bech JN, Nielsen CB, Ivarsen P, Jensen KT, and Pedersen EB. Dietary sodium affects systemic and renal hemodynamic response to NO inhibition in healthy humans. Am J Physiol Renal Physiol 274: F914–F923, 1998.
2. Effects of systemic NO synthesis inhibition on RPF, GFR, UNa, and vasoactive hormones in healthy humans
3. Noninvasive measurement of the Bayliss effect in retinal autoregulation
4. Buerk DG, Riva CE, and Cranstoun SD. Frequency and luminance dependent blood flow and K+ ion changes during flicker stimuli in cat optic nerve head. Invest Ophthalmol Vis Sci 36: 2216–2227, 1995.
5. Nitric Oxide Has a Vasodilatory Role in Cat Optic Nerve Head during Flicker Stimuli
Cited by
222 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献