Allen A, Yanushka J, Fitzpatrick J H, Jenkins L W, Gilboe D D
Department of Neurosurgery, University of Wisconsin Medical School, Madison 53706.
Acta Neuropathol. 1989;78(6):637-48. doi: 10.1007/BF00691291.
The acute cortical response to surgical brain isolation and subsequent extracorporal normoxic or 30 min hypoxic (PaO2 = 20 mm Hg) perfusions (hypoxic hypoxia with relative ischemia) was evaluated. Cerebral blood flow, arterial pH and CO2 were maintained constant during both perfusions; only the arterial oxygen content was changed. The isolated brain model used in this and previous investigations produces no qualitative ultrastructural changes in the neocortex following brain isolation and normoxic perfusion. However, the acute cortical structural response to 30 min of hypoxic hypoxia with relative ischemia demonstrated a number of important observations. Hypoxic hypoxia produced ultrastructural responses common to cerebral ischemia such as nuclear chromatin clumping, nucleolar condensation and cytoskeletal breakdown. Although neuronal abnormalities seen after 30 min of hypoxic hypoxia were similar to those acute neuronal changes observed following complete cerebral ischemia without recirculation, they differed three ways: (a) mitochondrial swelling and microvacuolation were observed in many cortical pyramidal neurons. (b) Glycogen particles within astroglial processes were observed even after a 30-min period of hypoxic hypoxia. (c) Perivascular astroglial swelling was minimal despite considerable perineuronal swelling. In contrast, incomplete cerebral ischemia produces mitochondrial changes similar to those in hypoxic hypoxia but also causes the depletion of tissue glycogen and perivascular glial swelling. Thus, hypoxic hypoxia with relative ischemia produces a unique acute ultrastructural response compared to either complete or incomplete cerebral ischemia.
评估了手术性脑隔离及随后的体外常氧或30分钟低氧（动脉血氧分压=20mmHg）灌注（伴有相对缺血的低氧性缺氧）引起的急性皮质反应。在两种灌注过程中，脑血流量、动脉血pH值和二氧化碳均保持恒定；仅动脉血氧含量发生变化。本研究及之前研究中使用的脑隔离模型在脑隔离及常氧灌注后，新皮质未产生定性的超微结构变化。然而，伴有相对缺血的30分钟低氧性缺氧引起的急性皮质结构反应有一些重要发现。低氧性缺氧产生了脑缺血常见的超微结构反应，如核染色质凝聚、核仁浓缩和细胞骨架破坏。虽然低氧性缺氧30分钟后出现的神经元异常与完全性脑缺血且无再灌注后观察到的急性神经元变化相似，但在三个方面有所不同：（a）在许多皮质锥体细胞中观察到线粒体肿胀和微空泡形成。（b）即使在低氧性缺氧30分钟后，星形胶质细胞突起内仍可观察到糖原颗粒。（c）尽管神经元周围有相当程度的肿胀，但血管周围星形胶质细胞肿胀轻微。相比之下，不完全性脑缺血产生的线粒体变化与低氧性缺氧相似，但也会导致组织糖原耗竭和血管周围胶质细胞肿胀。因此，与完全性或不完全性脑缺血相比，伴有相对缺血的低氧性缺氧产生了独特的急性超微结构反应。
