Blood flow velocity response of the ophthalmic artery and anterior optic nerve head capillaries to carbogen gas in the rhesus monkey model of optic nerve head ischemia.
OBJECTIVE
To determine the effect on blood flow velocity of the ophthalmic artery and anterior superficial optic nerve head (ONH) capillaries by changing inhaled gas from 100% oxygen to carbogen (95% oxygen, 5% CO(2)) in rhesus monkeys receiving chronic unilateral orbital endothelin-1 administration.


METHODS
The right eye of six young male rhesus monkeys (Macaca mulatta) received endothelin-1 (ET-1) by osmotic minipumps to the perineural optic nerve (0.3 microg/day) for 8 months. Three additional monkeys (control group) received the ET-1 vehicle (Sham) solution to the right optic nerve for the same period of time. The left eye served as a nontreated control in both groups. The blood flow velocities of the anterior ONH capillaries and ophthalmic artery were assessed in both eyes using confocal laser scanning flowmetry (CSLF) and color Doppler imaging (CDI), respectively.


RESULTS
A slight increase in the CDI blood flow velocities and a small decrease in the resistive index of the ophthalmic artery, and increased flow of the ONH capillaries in rhesus monkeys were detected when inhaled gas was changed from 100% oxygen to carbogen. The difference in CSLF blood flow in the nasal ONH between the endothelin-1 (ET-1) treated right eye and the normal left eye of the same individual monkeys was significantly greater than the difference in blood flow between the Sham-treated right eye and the normal left eye in control animals under the conditions of carbogen and oxygen inhalation.


CONCLUSIONS
Carbogen inhalation slightly influences the microcirculation of the globe and ONH in rhesus monkeys. These data suggest that low dose ET-1 administration has a subtle vasorelaxing effect in the ONH microcirculation in this animal model of ONH ischemia.
Brooks
Dennis E
DE
Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA. brooksd@mail.vetmed.ufl.edu
Komaromy
Andras M
AM
Kallberg
Maria E
ME
Miyabashi
Taka
T
Ollivier
Franck J
FJ
Lambrou
George N
GN
D000280:Administration, Inhalation; D000818:Animals; D001783:Blood Flow Velocity / Q000187:drug effects; D002245:Carbon Dioxide / Q000008:administration & dosage / Q000494:pharmacology; D007429:Intraocular Pressure / Q000187:drug effects; D017078:Laser-Doppler Flowmetry; D008253:Macaca mulatta; D008297:Male; D009880:Ophthalmic Artery / Q000502:physiology*; D009900:Optic Nerve / Q000098:blood supply*; D018917:Optic Neuropathy, Ischemic / Q000503:physiopathology / Q000662:veterinary*; D010100:Oxygen / Q000008:administration & dosage / Q000494:pharmacology; D012039:Regional Blood Flow / Q000187:drug effects
D002245:Carbon Dioxide; C011700:carbogen; D010100:Oxygen