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Peter Skov Jensen, Toke Bek; The dilating effect of glucose on retinal vessels differs at different vessel branching levels. Invest. Ophthalmol. Vis. Sci. 2018;59(9):5288.
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© ARVO (1962-2015); The Authors (2016-present)
Diabetic retinopathy is one of the most frequent causes of blindness in the Western World. Impaired retinal blood flow and changes in glucose concentration to the retina is involved in the pathophysiology of diabetic retinopathy. Recent studies have shown that the smaller and larger retinal vessels may contribute differently to changes in blood flow. However, the vasoactive effects of glucose on retinal vessels with different calibers have not been studied in detail. Therefore, the purpose of the present study was to study the effects of hypo- and hyperglycemia on the diameter of larger and smaller retinal vessels.
Porcine hemiretinas (n=23 in total) were mounted in an experimental model specifically developed for studying diameter changes of retinal vessels with different caliber. After preconstriction with the prostaglandin analogue U46619, the effects of hypoglycemia (2 mM glucose) and hyperglycemia (20 mM) 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 both arterioles, pre-capillary arterioles and capillaries U46619 induced contraction (preconstriction), but only significant for arterioles and precapillary arterioles (p<0.03), not capillaries. Following preconstriction the intravascular application of glucose with a concentration of 2 mM dilated both the arterioles and the capillaries significantly (p<0.01), but not the precapillary arterioles (p>0.65), while an intravascular application of glucose with a concentration of 20 mM dilated the arterioles and the precapillary arterioles significantly (p<0.03), but not capillaries (p>0.27).
The study has shown that glucose induced dilatation of retinal vessels differs at different branching levels and that the precapillary arterioles have a different sensitivity to glucose than other retinal vessel calibers. The different sensitivity to glucose in retinal vessels with different caliber confirms that retinal vessels with different diameter play a different role for regulating retinal blood flow. The pathways behind this mechanism need further investigation.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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