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重度急性和慢性高血压时,交感神经对脑循环起着重要的保护作用.从以下三个方面讨论这一作用的具体部位及其机制.一、急性血压升高时交感神经的作用:当血压急骤升高超过了脑血管的自动调节范围时,血管被动扩张,血流量猛增从而破坏血脑屏障.若同时刺激交感神经,可使脑血流量增加的幅度减低,并可保护血脑屏障不被破坏.为了明确血脑屏障受损的具体部位,作者进行了以下实验.给小鼠注射萤光右旋糖酐观察脑血管的动态变化.当输入苯肾上腺素使血压持续升高时,可见到血脑屏障首先在脑小静脉处破裂,尔后在毛细血管处破裂,有时偶而伴有在小动脉处破裂.同时,在输入
Sympathetic nerve plays an important role in cerebral circulation in severe acute and chronic hypertension.From the following three aspects to discuss the specific parts of the role and its mechanism.Acute blood pressure when the role of sympathetic: When the blood pressure Sudden increase in cerebral blood vessels beyond the automatic adjustment range, the passive expansion of blood vessels, blood flow so sharply damage the blood-brain barrier.If the sympathetic stimulation at the same time, can reduce the extent of increased cerebral blood flow, and can protect the blood-brain barrier Was destroyed.In order to clarify the specific part of the damaged blood-brain barrier, the author conducted the following experiment.Fluorescent dextran injection mice observed cerebrovascular dynamic changes.When the input phenylephrine blood pressure continued to rise, you can see the blood brain The barrier first ruptured at the vena cava, then ruptured at the capillaries, occasionally accompanied by rupture at the arterioles, and at the same time,