ABSTRACT
Objective To investigate the mechanism of unbalanced expressions of endothelin receptors (ETA/ETB )in cerebral vasospasm (CVS)after subarachnoid hemorrhage (SAH).Methods The rat CVS models were established by injecting autologous blood into the cisterna magna the second time.Basilar artery morphology was observed under light microscope and immunofluorescence staining was conducted to dynamically detect ETA/ETB receptor expression.Results The cross-sectional area of the basilar artery in the SAH model group decreased at 2 d to 3 d,and then gradually returned to normal.ETA receptor expression in endothelial cells of the basilar artery increased at 2 d after SAH,peaked at 3 d and remained increased till 14 d.ETB receptor expression increased significantly in endothelial cells at 3 d,peaked at 7 d and remained the same level till 14 d.Conclusion The results suggest that ETA/ETB receptors play an important role in cerebral vasospasm after SAH.The specific expression differences of ETB receptor subtypes in the brain vascular layers need further study.
ABSTRACT
Objective To investigate the effect of cerebral ischemia on functional parameters of affected arteries and probe into the possible pathogenesis of ischemia-reperfusion injury.Methods Intraluminal suture ischemic model was used by occlusion of left middle cerebral artery in rats.Two hours later,the middle cerebral artery segments were isolated from both ischemia and control groups for measurement of changes in vessel diameter induced by increasing pressure and vasoactive compounds.And then,distensibility,myogenic tone,reactivity to 5-HT and ACh were calculated and compared between groups.Results In lower pressure range,ischemic vessels showed an increased myogenic tone(at 40 mm Hg,1 mm Hg=0.133 kPa,19.3%±0.4% vs 10.0%±0.2%,t=20.568,P=0.000)and decreased diameter.In higher pressure range,ischemic vessels showed an increased diameter.distensibility and decreased myogenic tone(at 120 mm Hg,12.0%±0.2% vs 21.8%±0.4%,t=-23.575,P=0.000).In normal pressure range,myogenic tone was not altered after ischemia. Both groups constricted to 5-HT and dilated to ACh,however,the response was significantly diminished after ischemla.Conclusion These findings demonstrate that contractile and diastolic function of affected artery was impaired after ischemia,a result that may contribute to ischemia-reperfusion injury by losing upstream cerebrovascular resistance and increasing perfusion on the microcirculation.