Theilen H, Schröck H, Kuschinsky W
Department of Physiology, University of Heidelberg, Germany.
Am J Physiol. 1993 Aug;265(2 Pt 2):H642-8. doi: 10.1152/ajpheart.1993.265.2.H642.
Previous studies have shown a complete plasma perfusion of all capillaries in the rat brain under normal physiological conditions. This raises the question under which experimental conditions nonperfused capillaries may show up in the brain. Two experimental models were investigated in rats. 1) Reduced cerebral blood flow (CBF) during incomplete forebrain ischemia: hemorrhagic hypotension was maintained for 30 min at a mean arterial blood pressure of 41 mmHg. During the final 5 min of hypotension both carotid arteries were ligated. 2) Reperfusion after incomplete forebrain ischemia: reperfusion lasted for 4 h after either 15 or 30 min of incomplete forebrain ischemia. Under both experimental conditions, the density of the existing as well as the plasma-perfused brain capillary network was quantified using fluorescent double staining. Local CBF was measured during incomplete forebrain ischemia using the quantitative autoradiographic 4-iodo-[N-methyl-14C]antipyrine technique. The results showed a decrease in CBF during incomplete forebrain ischemia, which amounted up to 94%. Whereas normotensive control animals showed a complete staining of all capillaries within 5 s after the intravenous injection of Evans blue, this period of time was increased to 10 s during incomplete forebrain ischemia, indicating a delayed capillary perfusion. Four hours of reperfusion after 15 min of incomplete forebrain ischemia resulted in a complete capillary staining, whereas reperfusion after 30 min of ischemia was followed by intracerebral bleedings and a few nonperfused capillary areas (circulation time of Evans blue: 10 s).(ABSTRACT TRUNCATED AT 250 WORDS)
先前的研究表明，在正常生理条件下大鼠脑内所有毛细血管均有完整的血浆灌注。这就引出了一个问题，即在何种实验条件下脑内会出现未灌注的毛细血管。在大鼠身上研究了两种实验模型。1）不完全性前脑缺血期间脑血流量（CBF）降低：在平均动脉血压为41 mmHg的情况下维持出血性低血压30分钟。在低血压的最后5分钟，结扎双侧颈动脉。2）不完全性前脑缺血后的再灌注：在不完全性前脑缺血15或30分钟后再灌注持续4小时。在这两种实验条件下，使用荧光双重染色对现存的以及血浆灌注的脑毛细血管网络密度进行定量。在不完全性前脑缺血期间，使用定量放射自显影4-碘-[N-甲基-14C]安替比林技术测量局部脑血流量。结果显示，不完全性前脑缺血期间脑血流量降低，降幅高达94%。正常血压的对照动物在静脉注射伊文思蓝后5秒内所有毛细血管均完全染色，而在不完全性前脑缺血期间，这个时间延长至10秒，表明毛细血管灌注延迟。不完全性前脑缺血15分钟后再灌注4小时导致毛细血管完全染色，而缺血30分钟后再灌注则出现脑内出血和一些未灌注的毛细血管区域（伊文思蓝循环时间：10秒）。（摘要截短于250字）
