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Losartan and Ozagrel Reverse Retinal Arteriolar Constriction in Non‐Obese Diabetic Mice
Author(s) -
Lee Seungjun,
Harris Norman R.
Publication year - 2008
Publication title -
microcirculation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.793
H-Index - 83
eISSN - 1549-8719
pISSN - 1073-9688
DOI - 10.1080/10739680701829802
Subject(s) - losartan , vasoconstriction , arteriole , retinal , constriction , endocrinology , medicine , microcirculation , angiotensin ii , venule , thromboxane , chemistry , vasodilation , blood pressure , platelet , biochemistry
Objective: Reductions in retinal blood flow are observed early in diabetes. Venules may influence arteriolar constriction and flow; therefore, we hypothesized that diabetes would induce the constriction of arterioles that are in close proximity to venules, with the constriction mediated by thromboxane and angiotensin II. Methods: Using nonobese diabetic (NOD) mice, retinal measurements were performed three weeks following the age at which glucose levels exceeded 200 mg/dL, with accompanying experiments on age‐matched normoglycemic NOD mice. The measurements included retinal arteriolar diameters and red blood cell velocities and were repeated following an injection of the thromboxane synthase inhibitor, ozagrel. Mice were subdivided into equal groups and given drinking water with or without the angiotensin II receptor antagonist, losartan. Results: Retinal arterioles were constricted in hyperglycemic mice, with a significant reduction in flow. However, not all arterioles were equally affected; the vasoconstriction was limited to arterioles that were in closer proximity to venules. The arteriolar vasoconstriction (mean arteriolar diameters = 51 ± 1 vs. 61 ± 1 μ m in controls; p < 0.01) was eliminated by both ozagrel (61 ± 2 μ m) and losartan (63 ± 2 μ m). Conclusions: Venule‐dependent arteriolar vasoconstriction in NOD mice is mediated by thromboxane and/or angiotensin II.

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