Effects Of Human Urinary Kallikrein On Cerebral Blood Flow Following Permanent Middle Cerebral Artery Occlusion In Rats By Laser Speckle Imaging

Objective To study the effects of human urinary kallikrein on cerebral blood flow in hemispheric cortical area and MCA territory following permanent middle cerebral artery occlusion(pMCAO) in rats by laser Speckle Imaging.Methods Permanent middle cerebral artery occlusion(MCAO)was induced in male SD rats by the intraluminal filament technique. Laser Speckle Imaging was used to measure CBF in hemispheric cortical area and MCA territory .The brain was stained with 2,3,5-triphenyltetrazolium chloride(TTC) to determine infarct size.Functional outcomes were measured by neurological deficit. Result CBF increased both in hemispheric cortical area and MCA territory at the fisrt day and the second day after urinary kallikrein administration in high dose groups but not in low dose group(P <0.01). Whereas greater blood diameter and increased blood flow velocity were noticed in high dose groups in part of the arteries compared with low dose group and normal saline controls.Thirty six hours after the onset of MCAO,the brain infarct size was 10.14%±3.02%,25.99%±3.90%and 27.10%±3.32% in high,low dose and normal saline groups,respectively.The infarct size was significantly smaller in high(P <0.01) but not in low dose kallikrein treated animals compared with normal saline controls(P >0.05).Better functional improvement was shown in the high dose group rather than other two groups at 4h after cerebral ischemia(P <0.01),however, no differences in all the groups at 36h after MCAO(P >0.05).Conclusion Human urinary kallikrein can reduce brain infarct size and neurological deficit attributing to improve CBF in hemispheric cortical area and MCA territory and reopen the collateral circulation.