Premium
Inhibition of NO and COX products modifies the hypoxia‐induced dilatation of retinal vessels in vivo
Author(s) -
KAYA M,
PEDERSEN L,
BEK T
Publication year - 2014
Publication title -
acta ophthalmologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.534
H-Index - 87
eISSN - 1755-3768
pISSN - 1755-375X
DOI - 10.1111/j.1755-3768.2014.f043.x
Subject(s) - retinal , hypoxia (environmental) , isometric exercise , medicine , perfusion , endothelin 1 , stimulation , in vivo , blood flow , anesthesia , endocrinology , ophthalmology , chemistry , biology , oxygen , receptor , microbiology and biotechnology , organic chemistry
Purpose Retinal hypoxia with consequent changes in blood perfusion is a central feature in common vision threatening diseases. The aim of this study was to examine the effects of inhibiting COX and NO‐synthesis on hypoxia‐induced relaxation of retinal vessels in humans Methods Twenty healthy persons aged 20‐55 years were examined on two days separated by 4‐7 days. The resting diameter and the diameter response to isometric exercise and flicker stimulation of retinal vessels were studied using the Dynamic Vessel Analyzer before and during breathing a hypoxic gas mixture and before and during intravenous infusion with the NOS inhibitor L‐NMMA and were repeated on a second day after topical administration of the COX‐inhibitor diclofenac Results The resting diameter of arterioles increased significantly during hypoxia and decreased significantly during L‐NMMA infusion (p<0.0001) whereas no change in diameter was observed with the two applied together. When hypoxia and L‐NMMA were applied simultaneously, the gain factor was significantly lower than 1 (p=0.002) indicating that when diameter changes were corrected for changes in arterial blood pressure the blood flow increased, whereas this was not the case for either of the two interventions alone. Diclofenac significantly reduced contraction of retinal arterioles induced by isometric exercise (p=0.04) but not by the other interventions. Flicker‐induced dilatation of retinal arterioles was increased during L‐NMMA infusion (p<0.0001) but not during the other interventions Conclusion Diameter changes of retinal vessels during hypoxia are influenced by NO and COX products. This may point to new treatment strategies for diseases characterized by retinal hypoxia and disturbances in retinal perfusion