D'Alecy L G, Rose C J, Sellers S A
Circ Res. 1979 Dec;45(6):771-85. doi: 10.1161/01.res.45.6.771.
We measured cerebral blood flow using both the radioactive microsphere technique and the cerebral venous outflow technique in dogs anesthetized with chloralase. The effect of sympathetic stimulation on cerebral blood flow was observed during both normocapnia and prolonged hypercapnia using both blood flow techniques. The increase in blood flow with hypercapnia was the same with both methods. During hypercapnia the venous outflow method showed a 38% decrease and microspheres an 18% decrease in cerebral blood flow with sympathetic stimulation. At normal CO2, stimulation caused a decrease in cerebral venous flow: no change was observed with the microsphere method. Analysis of the blood flow patterns to extracerebral tissues and evaluation of extracerebral arterial reference samples failed to prove the existence of axial streaming and subsequent skimming of microspheres within the cephalic circulation. It is concluded that direct electrical stimulation of the sympathetic innervation of the cerebral vessels is capable of reducing cerebral blood flow even during a profound hypercapnic vasodilation.
我们使用放射性微球技术和脑静脉流出技术，在使用氯醛糖麻醉的犬身上测量脑血流量。在正常碳酸血症和长时间高碳酸血症期间，使用这两种血流技术观察交感神经刺激对脑血流量的影响。两种方法测得的高碳酸血症时血流量的增加是相同的。在高碳酸血症期间，静脉流出法显示交感神经刺激时脑血流量减少38%，微球法显示减少18%。在正常二氧化碳水平时，刺激导致脑静脉血流减少：微球法未观察到变化。对脑外组织血流模式的分析以及对脑外动脉参考样本的评估未能证明在头部循环中存在微球的轴向流动和随后的掠过现象。得出的结论是，即使在深度高碳酸血症性血管舒张期间，直接电刺激脑血管的交感神经支配也能够减少脑血流量。
