Abstract
Purpose :
Diabetic retinopathy is a frequent cause of blindness in the Western World and impaired retinal blood flow leading to changes in retinal oxygenation is known to be involved in the pathophysiology of the disease. Recent studies have shown that retinal vessels with different caliber may contribute differently to the regulation of retinal blood flow. The purpose of the present study was to assess whether the effects of hypoxia on the vessel diameter also differed among smaller and larger retinal vessels and to study whether the effect depended on nitric oxide.
Methods :
Porcine hemiretinas were mounted in an experimental setup developed for the study of diameter changes in retinal vessels with different caliber. After preconstriction with the prostaglandin analogue U46619, the effects of hypoxia on the diameter of larger arterioles (25 μm or larger), pre-capillary arterioles (10-25 μm) and capillaries (smaller than 10 μm) were studied in retinal vessels in the presence of the nitric oxide synthase inhibitor (L-NAME) or not (n=6 for both series).
Results :
Hypoxia caused dilatation of all vessel types of 16.0%±4.4%, (mean±SEM) and there was no significant difference between the effect in different vessel calibers (p>0.89, one-way ANOVA). The presence of L-NAME had no effect on hypoxia induced vasodilatation in any of the three vessel calibers (p > 0.35 for all comparisons, unpaired t-test).
Conclusions :
The vasodilating effect of hypoxia is similar in large and small retinal vessels, and the effect is mediated by other factors than nitric oxide.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.