Effects of dopamine on human retinal vessel diameter and its modulation during flicker stimulation.
We performed a randomized, subject-blinded, placebo and time-controlled, two-way crossover study in 12 healthy male subjects. Placebo or dopamine was administered on two separate study days. After saline infusion, dopamine hydrochloride was infused in three consecutive doses (5, 10, and 15 microg x kg(-1) x min(-1)). Plasma levels of dopamine were determined at each perfusion step. Arterial and venous retinal vessel diameters were measured with the use of a Zeiss retinal vessel analyzer. Diffuse luminance flicker stimuli of 8 Hz were applied for 60 s. Blood pressure and pulse rate were monitored continuously. Flicker stimulation (8 Hz) increased retinal vessel diameters under basal conditions. The response to 8-Hz flicker light was significantly reduced by dopamine administration. In addition, dopamine slightly but significantly increased retinal vessel diameters. Dopamine hydrochloride significantly increased systolic but not diastolic or mean arterial pressure. The present study indicates that dopamine has a distinct effect on retinal vessel diameters also attenuating the flicker-induced response reactivity of retinal vessels. This implies a role of dopamine in retinal blood flow hemodynamics.
Huemer
Karl-Heinz
KH
Department of Clinical Pharmacology, University of Vienna Medical School, Austria.
Garhofer
Gerhard
G
Zawinka
Claudia
C
Golestani
Elisabeth
E
Litschauer
Brigitte
B
Schmetterer
Leopold
L
Dorner
Guido T
GT
D000328:Adult; D004298:Dopamine / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D007275:Injections, Intravenous; D008297:Male; D010775:Photic Stimulation / Q000379:methods*; D012171:Retinal Vessels / Q000187:drug effects* / Q000502:physiology; D016037:Single-Blind Method; D014664:Vasodilation
D004298:Dopamine