Faraci F M, Mayhan W G, Werber A H, Heistad D D
Department of Internal Medicine, University of Iowa College of Medicine, Iowa City 52242.
Circ Res. 1987 Nov;61(5 Pt 2):II102-6.
The first goal of this study was to examine bilateral effects of reflex activation of sympathetic nerves on the cerebral circulation. Seizures, which activate sympathetic nerves, were induced in animals with intact nerves and after bilateral cervical sympathetic denervation. Increases in cerebral blood flow (microspheres) and decreases in cerebral vascular resistance were similar in denervated and innervated animals. Thus, during intense metabolic stimulation, metabolic factors are the primary determinant of cerebral blood flow, and bilateral effects of sympathetic nerves are minimal. The second goal of this study was to examine the role of vascular hypertrophy in protection of the cerebral circulation. Cerebral perfusion pressure was decreased on one side by clipping one carotid artery in 4-week-old stroke-prone spontaneously hypertensive rats. Two to four months later, the clip was removed, and seizures were induced. Disruption of the blood-brain barrier in the cerebrum occurred predominantly on the clipped side. We suggest that reduction in perfusion pressure attenuates development of cerebral vascular hypertrophy and thereby increases susceptibility to disruption of the blood-brain barrier. Thus, hypertrophy of cerebral vessels during chronic hypertension may protect the cerebral circulation.
本研究的首要目标是探究交感神经反射激活对脑循环的双侧影响。在神经完整的动物以及双侧颈交感神经去神经支配后的动物中诱发激活交感神经的癫痫发作。去神经支配动物和有神经支配动物的脑血流量增加（微球法）以及脑血管阻力降低情况相似。因此，在强烈的代谢刺激过程中，代谢因素是脑血流量的主要决定因素，交感神经的双侧影响极小。本研究的第二个目标是研究血管肥大在保护脑循环中的作用。在4周龄易患中风的自发性高血压大鼠中，通过夹闭一侧颈动脉使一侧脑灌注压降低。2至4个月后，移除夹子并诱发癫痫发作。大脑中血脑屏障的破坏主要发生在夹闭侧。我们认为灌注压降低会减弱脑血管肥大的发展，从而增加血脑屏障被破坏的易感性。因此，慢性高血压期间脑血管的肥大可能会保护脑循环。
