Sun M K, Guyenet P G
Am J Physiol. 1985 Dec;249(6 Pt 2):R672-80. doi: 10.1152/ajpregu.1985.249.6.R672.
A total of 45 cells with spinal projections, pulse-synchronous discharges, and extreme sensitivity to changes in arterial pressure were recorded in the retrofacial portion of nucleus paragigantocellularis lateralis (PGCL) in halothane-anesthetized rats. Every unit tested was inhibited by iontophoretic applications of gamma-aminobutyric acid (GABA), glycine, and taurine and excited by glutamate or the GABA receptor antagonist bicuculline methiodide. The inhibitory effect of GABA was antagonized by bicuculline methiodide but not by strychnine; the effect of glycine was eliminated by strychnine but unaffected by bicuculline. Iontophoretically applied bicuculline completely antagonized the time-locked reduction in unit activity resulting from increases in arterial pressure while strychnine was ineffective. 1-Glutamate, applied in a dose that produced a larger increase in the unit discharge rate than bicuculline, did not significantly alter the magnitude of the inhibition associated with increases in arterial pressure. It is concluded that GABA or a related substance mediates the inhibition of PGCL reticulospinal neurons resulting from the activation of arterial baroreceptors.
在氟烷麻醉的大鼠外侧巨细胞旁核（PGCL）的面神经后区域，共记录到45个具有脊髓投射、脉冲同步放电且对动脉压变化极度敏感的细胞。每个被测试的单位都受到离子导入γ-氨基丁酸（GABA）、甘氨酸和牛磺酸的抑制，并被谷氨酸或GABA受体拮抗剂甲磺酸荷包牡丹碱兴奋。GABA的抑制作用被甲磺酸荷包牡丹碱拮抗，但不被士的宁拮抗；甘氨酸的作用被士的宁消除，但不受甲磺酸荷包牡丹碱影响。离子导入甲磺酸荷包牡丹碱完全拮抗了因动脉压升高导致的单位活动的时间锁定减少，而士的宁则无效。以比甲磺酸荷包牡丹碱产生更大单位放电率增加的剂量应用L-谷氨酸，并未显著改变与动脉压升高相关的抑制幅度。得出的结论是，GABA或一种相关物质介导了动脉压力感受器激活导致的PGCL网状脊髓神经元的抑制。
