Estimation of oxygen delivery during cerebral ischemia and the consequent tissue damage.

使用近红外激光分光光度法（NIR）和磁共振成像（MRI）估计脑缺血期间的氧输送。采用免疫组化技术（MAP2染色）检测相应的组织损伤及其在药物作用下的衰减。脑缺血时的供氧：沙鼠双侧颈总动脉闭塞8分钟后产生脑缺血。缺血时脑供氧显著减少，近红外和核磁共振证实了这一点。脑缺血后的组织损伤：在上述缺血刺激7天后，沙鼠用固定液灌注。取脑组织，行MAP2染色。两海马CA1区均可见明显的缺血军团。新蝶呤（NP）对沙鼠缺血性神经元损伤的影响：缺血前给予NP （3mg/kg）可减轻沙鼠缺血性神经元损伤。NP可能通过解毒缺血再灌注过程中产生的氧自由基来预防缺血损伤。新蝶呤（NP）清除氧自由基的机理：在次黄嘌呤-黄嘌呤氧化酶和中性粒细胞-肉豆酸酯反应体系中，用电子顺磁共振（EPR）检测了NP清除氧自由基的活性。结果表明，NPH-4 （NP的还原形式）对两种系统中产生的氧自由基均有解毒作用，而NP本身则抑制氧自由基的产生。

Oxygen delivery during cerebral ischemia was estimated using a near infrared laser spectrophotometry (NIR) and magnetic resonace imaging (MRI). The consequent tissue damage and its attenuation by drugs were examined using an immunohistochemical technique (MAP2 stain).1. Oxygen delivery during cerebral ischemia : Cerebral ischemia was produced in a gerbil by occluding the bilateral common carotid arteries for 8 min. Oxygen delivery to brain reduced dramatically during ischemia, which was confirmed by NIR and MRI.2. Tissue damage following cerebral ischemia : Seven days after the above-mentioned ischemic challenge, the gerbils were perfused by a fixative. The brain was removed and its slices were stained by MAP2. Ischemic legions were clealy detected in the CA1 region of both hippocampi.3. Effects of neopterin (NP) on ischemic neuronal damages : The preischemic administration of NP (3mg/kg) attenuated ischemic neuronal damages in gerbils. NP may prevent the ischemic injury by detoxicating oxygen free radicals generated during ischemia-reperfusion.4. Mechanism of oxygen free radical scavenging by neopterin (NP) : In the hypoxanthine-xanthine oxidase and the neutrophil-phorbol myristate acetate reaction systems, the oxygen free radical scavenging activity of NP was examined using an electron paramagnetic resonance (EPR). The results indicated that NPH-4 (the reduced form of NP) detoxicated the generated oxygen free radicals in the both systems, while NP itself suppressed the oxygen free radical generation.