Peripheral endothelial dysfunction in normal pressure glaucoma.
OBJECTIVE
To assess vascular endothelial function in patients with normal pressure glaucoma using forearm blood flow responses to intra-arterial infusions of endothelial-dependent and -independent vasoactive agents.


METHODS
Eight patients with newly diagnosed and untreated normal pressure glaucoma and eight healthy age- and sex-matched control volunteers underwent measurement of forearm blood flow using venous occlusion plethysmography. Blood flow was assessed in response to incremental doses of sodium nitroprusside (an endothelial-independent vasodilator), acetylcholine (an endothelial-dependent vasodilator) and the vasoconstrictor N(G)-monomethyl-L-arginine (an inhibitor of nitric oxide synthase).


RESULTS
Sodium nitroprusside caused a dose-related increase in forearm blood flow in patients and controls. Glaucoma patients appeared to have an increased vasodilatory response, but this was not significant (P = 0.23). Acetylcholine also induced vasodilatation in both groups, but the response was significantly reduced in the glaucoma group (P = 0.04). N(G)-monomethyl-L-arginine induced a similar degree of vasoconstriction in both groups (P = 0.76).


CONCLUSIONS
This study has shown an impairment of peripheral endothelium-mediated vasodilatation in normal pressure glaucoma. These findings would support the concept of a generalized vascular endothelial dysfunction in patients with this condition.
Henry
E
E
Princess Alexandra Eye Pavilion, Edinburgh.
Newby
D E
DE
Webb
D J
DJ
O'Brien
C
C
D000109:Acetylcholine / Q000008:administration & dosage; D001783:Blood Flow Velocity / Q000187:drug effects; D001916:Brachial Artery / Q000503:physiopathology*; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000503:physiopathology*; D004791:Enzyme Inhibitors / Q000008:administration & dosage; D005260:Female; D005542:Forearm / Q000098:blood supply; D005902:Glaucoma, Open-Angle / Q000503:physiopathology*; D006801:Humans; D007261:Infusions, Intra-Arterial; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D009599:Nitroprusside / Q000008:administration & dosage; D010991:Plethysmography; D014665:Vasodilator Agents / Q000008:administration & dosage; D019323:omega-N-Methylarginine / Q000008:administration & dosage
D004791:Enzyme Inhibitors; D014665:Vasodilator Agents; D009599:Nitroprusside; D019323:omega-N-Methylarginine; D019001:Nitric Oxide Synthase; D000109:Acetylcholine