Okada Y, Mückenhoff K, Scheid P
Institut für Physiologie, Ruhr-Universität Bochum, Germany.
Respir Physiol. 1993 Sep;93(3):327-36. doi: 10.1016/0034-5687(93)90078-o.
We have extracellularly recorded single neuron activity in the ventral medulla of the isolated brain stem-spinal cord preparation of the neonatal rat (37 preparations) in order to test their sensitivity to changes in CO2/H+. Search for neuronal activity was performed when the preparation was superfused with control mock CSF (equilibrated with 2% CO2, 90% O2 in N2; pH = 7.8 at 27 degrees C). Neurons, found down to about 500 microns from the surface, could be classified as R neurons when they showed rhythmic discharge in phase with phrenic activity, recorded from C4 ventral roots; or as Non-R neurons when they did not exhibit such phasic discharge. Among the 89 Non-R neurons, 20 responded to rapidly replacing the control CSF by hypercapnic CSF (8% CO2, 90% O2 in N2; pH = 7.2) with increased, 44 with reduced activity, while 25 did not respond to hypercapnia. Five Non-R neurons became phasic with respiration during hypercapnia. Of the 14 R neurons, 10 fired predominantly in expiration (R-E), 4 in inspiration (R-I). Only one R-E and two R-I neurons were excited by hypercapnia, the remaining were either inhibited or did not respond. Excited Non-R and R neurons were mainly encountered in rostral parts of those areas in the ventral medulla that have been reported as chemosensitive.
我们在新生大鼠离体脑干-脊髓标本的延髓腹侧进行了细胞外单神经元活动记录（共37个标本），以测试它们对CO2/H+变化的敏感性。当标本用对照模拟脑脊液（用2% CO2、90% O2和N2平衡；27℃时pH = 7.8）灌流时，开始寻找神经元活动。在距表面约500微米深处发现的神经元，若其放电节律与从C4腹根记录到的膈神经活动同步，则可归类为R神经元；若不表现出这种阶段性放电，则归类为非R神经元。在89个非R神经元中，20个对用高碳酸血症脑脊液（8% CO2、90% O2和N2；pH = 7.2）快速替换对照脑脊液有反应，活动增加，44个活动减少，而25个对高碳酸血症无反应。5个非R神经元在高碳酸血症期间与呼吸同步放电。在14个R神经元中，10个主要在呼气时放电（R-E），4个在吸气时放电（R-I）。只有1个R-E神经元和2个R-I神经元被高碳酸血症兴奋，其余的要么被抑制，要么无反应。兴奋的非R神经元和R神经元主要出现在延髓腹侧那些已被报道为化学敏感区的头端部分。
