Taylor R B, Weaver L C
John P. Robarts Research Institute, University of Western Ontario, London, Canada.
Am J Physiol. 1993 Jun;264(6 Pt 2):R1193-9. doi: 10.1152/ajpregu.1993.264.6.R1193.
After spinal cord transection in cats and rats, the activity of many sympathetic nerves is not entirely lost, and firing of other nerves continues unabated or is increased. This study was done to evaluate the importance of dorsal root afferent discharge on the generation of tonic sympathetic activity in renal and mesenteric postganglionic nerves in spinal rats and in rats with intact neuraxes. Sympathetic discharge was recorded in anesthetized rats, and peripheral afferent influences were eliminated by dorsal rhizotomy from T4 to L2. Activity of renal and mesenteric nerves was well maintained after high cervical and thoracic (T4) cord transections. Rhizotomy had no effect on sympathetic discharge in rats with intact neuraxes but decreased renal nerve activity significantly (-25%) in spinal rats. Because rhizotomy decreased mesenteric discharge in only three of six spinal rats, mean mesenteric nerve discharge was not decreased significantly. The decreased renal nerve discharge after dorsal rhizotomy could not be attributed to input from any specific spinal segment, and ipsilateral input was no greater than contralateral input. After rhizotomy, both renal and mesenteric nerves had substantial excitatory drive from the transected, deafferented spinal cord. These findings demonstrate that dorsal root afferent influences on spinal neurons can contribute to the generation of tonic discharge in some sympathetic nerves in spinal animals.
在猫和大鼠的脊髓横断后，许多交感神经的活动并未完全丧失，其他神经的放电持续不减或增加。本研究旨在评估背根传入放电对脊髓大鼠和神经轴完整大鼠肾和肠系膜节后神经紧张性交感活动产生的重要性。在麻醉大鼠中记录交感神经放电，并通过T4至L2的背根切断术消除外周传入影响。在高位颈髓和胸髓（T4）横断后，肾和肠系膜神经的活动得到良好维持。背根切断术对神经轴完整的大鼠的交感神经放电没有影响，但在脊髓大鼠中显著降低了肾神经活动（-25%）。由于背根切断术仅在六只脊髓大鼠中的三只中降低了肠系膜放电，因此平均肠系膜神经放电没有显著降低。背根切断术后肾神经放电的减少不能归因于任何特定脊髓节段的输入，同侧输入也不大于对侧输入。背根切断术后，肾和肠系膜神经均受到来自横断、去传入脊髓的大量兴奋性驱动。这些发现表明，背根传入对脊髓神经元的影响可有助于脊髓动物某些交感神经紧张性放电的产生。
