Journal: Cardio-oncology

Article Title: Radiation- and age-related vascular dysfunction as an early indicator of cardiovascular risk: a long-term study in the ApoE −/− mouse model of atherosclerosis

doi: 10.1186/s40959-025-00395-6

Figure Lengend Snippet: Experimental set-up for irradiation and OCT-imaging of the murine Arteria saphena. A For irradiation in the X-ray device (1), anesthetized animals were positioned on their left side and secured on a Plexiglas holder. The bent right leg and lower abdomen were shielded with lead to protect them from radiation, ensuring that only the inner side of the left lower leg remained within the irradiation field. The exposure area beneath the irradiation window was defined by a collimator plate made of a bismuth-lead-tin alloy (MCP-96) with copper cutouts (2). Up to five animals were irradiated simultaneously on an underlying Plexiglas plate (3). The mesures are given in centimeters. B The OCT system for vascular imaging of the A. saphena operates using near-infrared light emitted by a diode (1), which is transmitted to the scanner head (2) via fiber optic cables (3). Within the scanner head the incoming light is collimated to a beam of 2.4 mm in diameter through a collimator (4) (focal length = 12 mm) and subsequently divided into a reference and probe beam of equal diameter with a beam splitter. To scan the arterial surface, the probe beam is diffracted via two galvanometric scanners (5) (Cambridge Technologies, Planegg) and focused through an achromatic lense (6) (focal length = 25.4 mm, diameter = 15 mm). The light reflected by the arterial surface and the reference beam that has been reflected by a mirror are then recombined by the beam splitter. Fiber optic cables lead the resulting interference signal through a collimator (focal length = 40 mm) and to a spectrometer to be spectrally analyzed with a diffraction grating (1200 lines/mm). The interference spectrum is then focused through an achromatic lense (focal length = 75 mm) and detected with a silicon detector (LIS-1024, pixel size: 7.8 μm × 125 μm × 1024 px, Photon Vision Systems Inc., Homer, USA). A Fast Fourier Transform of the interference signal provides depth-resolved information about the arterial tissue. C Representative recording of the A. saphena (white arrows) and Vena saphena medialis (grey arrows) of a C57BL/6 mouse aged 8 weeks, one day after irradiation with 2 Gy. The upper picture row in the foreground represents 2-D cross sectional OCT-images. The picture row below in the background are video-recordings to orientate on the tissue. Left: Vessel diameter at rest after application of physiological buffer solution. Middle: Arterial vasoconstriction (VC) after application of buffer solution with high potassium concentration (K+). Right: Arterial vasodilation (VD) induced by sodium nitroprusside (SNP). The diameter of the saphenous vein was unaffected. Below: Time course of inner diameter changes of A. saphena with fitted sigmoid function (black line). d0: initial diameter, dVC: minimal diameter during VC. dVD: maximal diameter during VD. t 1/2 : time of half VC or VD

Article Snippet: To assess the arterial diameter at baseline the exposed A. saphena was moistened with a physiological buffer solution (NaCl: 119 mmol/l, Merck, Darmstadt, Germany; KCl: 4.7 mmol/l, Merck; MgSO 4 : 1.17 mmol/l, Sigma-Aldrich, Taufkirchen, Germany; NaHCO 3 : 25 mmol/l, Merck; KH 2 PO 4 : 1.18 mmol/l, Merck; Glucose: 5.5 mmol/l, Merck; EDTA: 0.027 mmol/l, Prolabo, VWR International, Darmstadt) right before starting OCT. Acquisition of the baseline diameter stopped automatically after 30 initial B-scans (equivalent to a recording time of 7.5 s).

Techniques: Irradiation, Imaging, Concentration Assay