Iriuchijima J
Department of Physiology, School of Medicine, University of Hiroshima, Japan.
Jpn J Physiol. 1990;40(6):907-14. doi: 10.2170/jjphysiol.40.907.
Rats, chronically instrumented with an electromagnetic flow probe around the carotid, superior mesenteric, or renal artery, or the terminal aorta as well as having an arterial and venous catheter, were anesthetized with either and submitted to high spinal cord transection. One hour later, when the rats had recovered consciousness and the arterial pressure had recovered partially, hexamethonium was intravenously injected for ganglionic blockade. Peripheral resistance (arterial pressure/regional flow) was decreased significantly by ganglionic blockade in the carotid and renal areas but not in the superior mesenteric and hindquarter (terminal aortic) areas. This suggests the presence of sizable vasoconstrictor tone to resistance vessels in the carotid and renal areas but not in the superior mesenteric and hindquarter areas in the acute spinal rat. This distribution of vasoconstrictor tone is similar to that in intact conscious rats in the resting state and suggests the possibility that the vasoconstrictor tone for resistance vessels in intact rats is also for the most part generated in the spinal cord. Spinal transection decreased blood flow in all the four regions, suggesting a decrease in cardiac output due to dilation of capacitance vessels. It is possible that, in intact rats at rest, the so-called medullary vasomotor center is sending tonic impulses for the most part to capacitance vessels.
大鼠长期在颈动脉、肠系膜上动脉、肾动脉或主动脉末端周围安装电磁流量探头，并插入动脉和静脉导管，然后用戊巴比妥钠麻醉，进行高位脊髓横断术。一小时后，当大鼠恢复意识且动脉压部分恢复时，静脉注射六甲铵进行神经节阻断。神经节阻断使颈动脉和肾区的外周阻力（动脉压/局部血流量）显著降低，但肠系膜上动脉和后肢（主动脉末端）区域未降低。这表明急性脊髓损伤大鼠的颈动脉和肾区阻力血管存在相当大的血管收缩张力，而肠系膜上动脉和后肢区域则不存在。这种血管收缩张力的分布与静息状态下完整清醒大鼠的情况相似，这表明完整大鼠阻力血管的血管收缩张力大部分也可能在脊髓产生。脊髓横断使所有四个区域的血流量减少，提示由于容量血管扩张导致心输出量减少。在静息状态下的完整大鼠中，所谓的延髓血管运动中枢很可能大部分时间都在向容量血管发送紧张性冲动。
