Laser doppler flow probe

We measured regional renal cortical blood flow (RRCBF) in the peri-arrest period. A laser Doppler flow probe (Moor Instruments, Wilmington, DE, USA) was placed perpendicular to the surface of the right kidney via a flank incision and optimally positioned for maximal signal. Laser Doppler flow was measured and recorded 5 min before CA, immediately before CA, every minute during CA, and every 5 min after CA for 45 min after ROSC for each animal treated with 17β-estradiol or vehicle at 15 min after ROSC. Fifty minutes after ROSC, arterial blood was aspirated from the left ventricle for blood gas assessment.

Focal cerebral ischaemia was induced in the left cerebral hemisphere (ipsilateral) by MCAO.^{30 (link)} Under isoflurane anaesthesia (2% in 200 ml/min O₂ and 500 ml/min N₂O), an intraluminal filament (filament diameter 70 µm, silicon coating diameter 210 µm, coating length 4–5 mm, Doccol, USA) was advanced via the left external carotid artery into the internal carotid artery until it occluded the middle cerebral artery (MCA) at its origin. After 20 min occlusion, the filament was withdrawn to allow reperfusion. Cerebral blood flow (CBF) was monitored throughout using a laser-flow blood perfusion monitor connected to a laser-Doppler flow probe (Moor instruments, UK) attached to the animal’s skull overlying the territory supplied by the MCA. Successful occlusion was confirmed by a reduction of at least 80% in CBF. Body temperature was maintained at 37℃ using a homeothermic heat mat (Harvard Apparatus, UK).