In vivo imaging of murine vasodynamics analyzing different mouse strains by optical coherence tomography.

BACKGROUND AND AIMS: We tried to circumvent the limitations of standard organ chamber experiments using in vivo optical coherence tomography (OCT) to analyze the vascular function of small arteries in different mouse strains.

METHODS: OCT images were acquired with a two-axis galvanometer scanner head. Time series (3 frames per second, 300 × 512 pixel per frame) of cross-sectional images were analyzed with image processing software measuring the time course of vessel lumen dynamics. Vascular function of murine saphenous artery of male C57BL/6 (wild-type) and hypercholesterolemic LDLR knockout (LDLR-/- ) mice was analyzed at 6 weeks and after 14 weeks feeding a control or high-fat diet containing 21.2% butter fat and 2.1 mg/kg cholesterol. Vasoconstriction and vasodilation was analyzed by OCT in response to 80 mM K+ and 1 mM SNP.

RESULTS: The OCT technique allowed determination of inner diameter, flow resistance, maximal velocity of diameter change and time to half-maximal diameter change in murine saphenous arteries of wild-type and LDLR-/- mice. LDLR-/- had impaired vasodilation and changes in vasodynamics after 14 weeks on control or high-fat diet, compared to wild-type mice. The diameter of the saphenous artery of LDLR-/- mice was reduced after vasoconstriction (38 ± 7 μm vs 12 ± 6 μm) and vasodilation (245 ± 8 μm vs 220 ± 10 μm) (P < 0.05 vs C57BL/6).

CONCLUSION: OCT was used as an innovative method to image vascular function of small arteries of wild-type and hypercholesterolemic LDLR-/- mice after high-fat diet. The method offers the ability to display differences in the vasodynamics at early stages of endothelial dysfunction in vivo.