L-arginine-derived nitric oxide: a major determinant of uveal blood flow.
The effect of inhibition of the L-arginine-nitric oxide pathway on regional ocular blood flow was studied in anaesthetized Beagle dogs. Under control conditions (mean arterial blood pressure 105 +/- 6 mmHg) trapping of 11 and 15-microns-diameter tracer microspheres revealed the following regional blood flows (ml min-1 g-1): retina 0.065 +/- 0.016, choroid 5.72 +/- 0.32, ciliary body 0.77 +/- 0.11, iris 0.18 +/- 0.04. After i.v. infusion of nitro-L-arginine methylester (20 mg kg-1), a potent inhibitor of nitric oxide production from L-arginine, mean arterial blood pressure increased from 105 +/- 6 mmHg by 19% to a new steady-state level of 125 +/- 7 mmHg. This increase of arterial blood pressure extended over 3 hr and was reversible after i.v. infusion of L-arginine (100 mg kg-1 over 10 min). Despite the increase in blood pressure following infusion of nitro-L-arginine methylester blood flow of choroid, ciliary body, and iris were significantly decreased by 40, 40 and 48%, respectively. Retinal blood flow did not change significantly (-12%). These results suggest that the L-arginine-nitric oxide pathway is of major importance for the adjustment of uveal blood flow under resting physiological conditions.
Deussen
A
A
Zentrum für Physiologie, Heinrich-Heine-Universität Düsseldorf, Germany.
Sonntag
M
M
Vogel
R
R
D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D002924:Ciliary Body / Q000098:blood supply; D004285:Dogs; D007498:Iris / Q000098:blood supply; D019331:NG-Nitroarginine Methyl Ester; D009569:Nitric Oxide / Q000378:metabolism*; D012039:Regional Blood Flow / Q000187:drug effects; D012171:Retinal Vessels / Q000502:physiology; D014602:Uvea / Q000098:blood supply*
D009569:Nitric Oxide; D001120:Arginine; D019331:NG-Nitroarginine Methyl Ester