阻滞面神经后核内侧区对呼吸节律的影响

实验在麻醉和切断双侧颈迷走神经的家兔上进行。以1％普鲁卡因对称地阻滞延髓闩前2.0—3.0mm、中线旁开2.2—2.5mm、背侧表面下3.5—4.5mm的区域能可逆地消除呼吸运动和膈神经节律性放电。对称地损毁该区则产生不可逆的呼吸停止。组织学检查证实,此区相当于Meessen图谱的面神经后核内侧区(mN-RF),包括面神经后核(N.rVII)内侧部、网状小细胞核(R.pc)腹侧部、网状巨细胞核(R.gc)的外侧部、外侧网状核(R.1)的内侧部。阻滞延髓的其他区域,除腹侧群呼吸神经元(VRG)的头端部分(该部分与mNRF有重叠)外,对呼吸节律无明显影响。在阻滞mNRF引起呼吸停止期间.延髓背侧群(DRG)与腹侧群尾端的呼吸性神经元放电的节律性消失,刺激DRG与VRG尾端区域,只能诱发短串的膈神经放电,而不能产生节律性的发放,说明该部呼吸性神经元本身无自动节律活动能力。结果提示面神经后核内侧区在发生和维持基本呼吸节律中起重要作用。

Effect of blocking medial area of nucleus retrofacialis on respiratory rhythm

Experiments were performed on anaesthetized,vagotomized rabbits. Respiratory movements and phrenic rhythmical discharges could be reversibly abolished by the symmetrical injection of 1% procaine in the medulla from 2.0-3.0mm rostral to the obex, 2.2-2.5mm lateral to the midline and 3.5-4.5mm ventral to the dorsal surface of medulla.Symmetrical lesions of this area resulted in non-reversible apnea. Histological examination verified that this area corresponded to the medial area of nucleus retrofacialis ( mNRF ) ,including the medial part of nucleus retrofacialis, the ventral part of nucleus reticularis parvocellularis, the lateral part of nucleus reticularis gigantocellularis and the medial part of nucleus reticularis lateralis according to Meessen's rabbit brain atlas. Blocking other areas of medulla had no obvious effect on respiratory rhythm, except the rostral portion of ventral respiratory group ( VRG). This portion overlaps with mNRF.When the blockade of mNRF was performed most inspiratory and expiratory neurons recorded in the VRG and DRG (dorsal respiratory group ) went progressively into continuous firing, without any respiratory rhythm. The minority of respiratory neurons were inactivated during apnea. Stimulation of caudal portion of DRG and VRG could evoke only short clusters of phrenic discharges instead of rhythmical firing, indicating respiratory neurons localized in these areas can not generate rhythmic activity themselves. This result suggests that the mNRF play an important role in the genesis and maintenance of basic respiratory rhythm.