Simultaneous observation of superficial cortical and intracerebral microvessels in vivo during reperfusion after transient forebrain ischemia in rats using synchrotron radiation

Using a newly developed angiography system that combines monochromatic synchrotron radiation (MSR) as an X-ray source with a high-definition camera or video system, we observed superficial cortical and intracerebral microvessels simultaneously in vivo during reperfusion after transient forebrain ischemia. Transient brain ischemia was induced by 10-min four-vessel occlusion in rats under general anesthesia. Angiographic images were then sequentially obtained at 3 frames/s. The detector features a 7-μm equivalent pixel size projected onto the input area and a 7 mm × 7 mm input field. Changes in the cerebral microvessels were observed before and 1, 5, 10, 15, 20 and 30 min after transient cerebral ischemia using the MSR angiography system. The calibers of the internal carotid artery (ICA), middle cerebral artery (MCA), and striate artery (SA) significantly increased 1 min after reperfusion, while the pial arteriole (PA) caliber significantly decreased (76% of base line). The MCA, PA and SA were significantly dilated 5 and 10 min after reperfusion. Although the caliber of the ICA significantly decreased after 30 min reperfusion compared with the basal value, the calibers of the other three vessels remained larger than the basal values throughout the experiment. Early venous filling was observed at 5 and 10 min after reperfusion. The MSR angiography system is useful for investigating morphological changes in both cortical and central branches of cerebral vessels in rats during reperfusion after cerebral ischemia.