De Ley G
Laboratorium voor Normale en Pathologische Fysiologie, Rijksuniversiteit Gent.
Verh K Acad Geneeskd Belg. 1990;52(5):413-54.
In order to gain more insight into the pathophysiology of extracerebral cerebrovascular occlusion, the cerebral hemodynamic behaviour after uni- or bilateral carotid occlusion was investigated. In Wistar rats, acute occlusion of one common carotid artery leads to a moderate bilateral lowering of the resting hemispheric brain blood flow; no interhemispheric perfusion asymmetry is observed. During hypercapnia, however, a manyfold increase of the hemispheric blood flow is seen at the intact side, whereas blood flow increase at the side of the occlusion is suppressed indicating that the cerebrovascular reserve at the side of the occlusion is largely used to preserve resting hemispheric perfusion. During the days (1, 5, 15 and 30) following the occlusion, resting hemispheric blood flow is progressively restored rather rapidly (bilateral normalization on the fifth day) whereas restoration of the cerebrovascular reserve (hemispheric blood flow increase in hypercapnia) proceeds more slowly and a nearly normal hypercapnic response is reached on day thirty. Spontaneously Hypertensive Rats (SHR) show structural abnormalities of their blood vessels during the development of hypertension, leading to impaired adaptation possibilities of the cerebral vasculature after unilateral common carotid occlusion. This is indicated by the striking comparability of the compensation of hemispheric cerebral blood flow (in normo- and hypercapnia) of SH rats five days after unilateral carotid occlusion with the cerebral hemodynamic status of normotensive animals already seen 24 hours after the same occlusion. Consecutive bilateral common carotid occlusion shows that survival rate increases by increasing the interval between both occlusions. This survival relation is much more unfavorable in SH rats. The parallelism between the restoration of the measured CO2-reactivity of the blood flow in the involved hemisphere after unilateral carotid occlusion and the evolution of survival rate after consecutive bilateral carotid occlusion indicates that the response of the hemispheric circulation to CO2 offers a good estimate of true cerebrovascular reserve after cerebrovascular accidents of this kind. In cats, acute bilateral occlusion of the carotid arteries leads to a moderate decrease of resting cerebral blood flow in the anterior parts of the brain (cerebrum); the hypercapnic response of this region is, however, completely abolished. In the posterior brain regions (medulla oblongata and cerebellum) resting blood flow and its increase under hypercapnia are preserved. The experiments indicate that the relative preservation of resting cerebral blood flow in the cerebrum of the cat after acute bilateral carotid occlusion is at the expense of its complete hemodynamic reserve. Posterior brain regions are better protected in these conditions.(ABSTRACT TRUNCATED AT 400 WORDS)
为了更深入了解脑外脑血管闭塞的病理生理学，研究了单侧或双侧颈动脉闭塞后的脑血流动力学行为。在Wistar大鼠中，急性闭塞一条颈总动脉会导致静息半球脑血流量出现中度双侧降低；未观察到半球间灌注不对称。然而，在高碳酸血症期间，完整侧的半球血流量会增加数倍，而闭塞侧的血流量增加受到抑制，这表明闭塞侧的脑血管储备在很大程度上用于维持静息半球灌注。在闭塞后的数天（1天、5天、15天和30天）内，静息半球血流量逐渐快速恢复（第5天双侧恢复正常），而脑血管储备的恢复（高碳酸血症时半球血流量增加）则进展较慢，在第30天达到接近正常的高碳酸血症反应。自发性高血压大鼠（SHR）在高血压发展过程中表现出血管结构异常，导致单侧颈总动脉闭塞后脑血管的适应能力受损。这表现为单侧颈动脉闭塞5天后SH大鼠半球脑血流量（在正常和高碳酸血症状态下）的代偿情况与正常血压动物在相同闭塞24小时后已观察到的脑血流动力学状态具有显著可比性。连续双侧颈总动脉闭塞表明，通过增加两次闭塞之间的间隔时间，存活率会提高。这种存活关系在SH大鼠中更为不利。单侧颈动脉闭塞后受累半球血流的测量二氧化碳反应性恢复与连续双侧颈动脉闭塞后存活率演变之间的平行关系表明，半球循环对二氧化碳的反应为这类脑血管意外后真正的脑血管储备提供了一个良好的估计。在猫中，急性双侧颈动脉闭塞会导致大脑前部（大脑）静息脑血流量适度降低；然而，该区域的高碳酸血症反应完全消失。在后脑区域（延髓和小脑），静息血流量及其在高碳酸血症时的增加得以保留。实验表明，猫急性双侧颈动脉闭塞后大脑中静息脑血流量的相对保留是以其完全的血流动力学储备为代价的。在这些情况下，后脑区域受到更好的保护。（摘要截断于400字）
