Altered nitric oxide system in patients with open-angle glaucoma.
OBJECTIVE
To investigate the ocular blood flow response to systemic nitric oxide synthase inhibition in patients with primary open-angle glaucoma.


METHODS
In 12 patients with glaucoma and 12 age-matched control subjects, subfoveal choroidal blood flow, optic nerve head blood flow, ocular fundus pulsation amplitude, intraocular pressure, and systemic hemodynamic parameters were measured at baseline and after inhibition of nitric oxide synthase by intravenous administration of NG-monomethyl-L-arginine.


RESULTS
The increase in blood pressure in response to NG-monomethyl-L-arginine was comparable between the 2 study cohorts. In patients with glaucoma, the decrease of optic nerve head blood flow (P = .03) and fundus pulsation amplitude (P<.001) during nitric oxide synthase inhibition was significantly less pronounced than in healthy control subjects. A tendency toward a reduced response in choroidal blood flow was seen (P = .051 between groups) in patients with glaucoma.


CONCLUSIONS
This is the first in vivo study providing evidence for an altered ocular L-arginine/nitric oxide system in patients with glaucoma. Normalization of the ocular nitric oxide production may be beneficial in terms of normalization of ocular blood flow and neuroprotection of retinal ganglion cells.
Polak
Kaija
K
Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria.
Luksch
Alexandra
A
Berisha
Fatmire
F
Fuchsjaeger-Mayrl
Gabriele
G
Dallinger
Susanne
S
Schmetterer
Leopold
L
D001783:Blood Flow Velocity; D001794:Blood Pressure; D002829:Choroid / Q000098:blood supply*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005902:Glaucoma, Open-Angle / Q000378:metabolism* / Q000503:physiopathology*; D006801:Humans; D007429:Intraocular Pressure; D017078:Laser-Doppler Flowmetry; D008875:Middle Aged; D009569:Nitric Oxide / Q000378:metabolism*; D052248:Nitric Oxide Synthase Type I / Q000037:antagonists & inhibitors; D052250:Nitric Oxide Synthase Type III / Q000037:antagonists & inhibitors; D009898:Optic Disk / Q000098:blood supply*; D012039:Regional Blood Flow; D019323:omega-N-Methylarginine / Q000494:pharmacology
D004791:Enzyme Inhibitors; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D052248:Nitric Oxide Synthase Type I; D052250:Nitric Oxide Synthase Type III