Effects of human urinary kallikrein on regional cerebral blood flow in penumbra following focal cerebral ischemia in rats

Objective To study the effects of human urinary kallikrein on regional cerebral blood flow (rCBF) in penumbra following focal cerebral ischemia in rats. Methods Permanent middle cerebral artery occlusion (MCAO) was induced in male SD rats by the intraluminal filament technique. Laser Doppler flowmetry was used to measure rCBF in ischemic core and penumbra. The brain was stained with 1% 2,3,5-triphenyltetrazolium chloride (TTC) to determine infarct size. Results rCBF in penumbra increased starting from 5 minutes and reached the peak at 20 minutes after urinary kallikrein administration in high and middle dose groups but not in low dose group. Twenty-four hours after the onset of MCAO, the brain infarct size was 16.44%±3.17%, 16.61%±2.76%, 28.58%±2.38% and 30.38%±2.76% in high,middle, low dose and normal saline groups, respectively. The infarct size was significantly smaller in high and middle but not in low dose kallikrein treated animals compared with normal saline controls (P0.05). Conclusions Human urinary kallikrein can reduce brain infarct size and improve rCBF in penumbra.