一氧化氮对呼吸节律性放电的调节作用

实验旨在探讨一氧化氮(nitric oxide,NO)在基本呼吸节律产生和调节中可能的作用。制作新生大鼠离体延髓脑片标本,主要包含面神经后核内侧区,前包钦格复合体、腹侧呼吸组以及背侧呼吸组的一部分。同时保留舌下神经根,用改良Kreb′s液灌流脑片并记录与之相连的舌下神经根呼吸节律性放电(respiratory rhythmical discharge activity,RRDA),在灌流液中分别给予不同浓度的NO供体硝普钠(sodium nitroprusside,SNP),NO合成前体L—精氨酸(L—Arginine,L-Arg)以及神经元型一氧化氮合酶(neuronal nitric oxide synthase,nNOS)特异性抑制剂7-nitro indazole (7-NI),观察其对RRDA的影响。结果显示,nNOS的特异性抑制剂7-NI对吸气时程和放电强度有明显抑制,而NO合成前体L—Arg,以及NO供体SNP对呼吸放电活动没有明显的影响。这提示,在哺乳动物基本呼吸节律的产生和调节中,NO可能对吸气中止和呼吸幅度具有调节作用。

Nitric oxide is involved in the modulation of central respiratory rhythm

This experiment was expected to test whether nitric oxide (NO) exerted significant effect onthe central respiratory rhythm. Experiments were performed on in vitro brainstem slice preparations fromneonatal rats. These preparations include the medial region of the nucleus retrofacialis (mNRF); a part ofpre-Botinger complex, ventral respiratory group (VRG) and dorsal respiratory group (DRG). Respiratory-related burst activities were recorded from hypoglossal nerve rootlets before and during superfusion of theslice preparation with L-Arginine (L-Arg), sodium nitroprusside (SNP) or 7-nitro indazole (7-NI, an in-hibitor of NO synthase). After perfusion with L-Arg and SNP, there was no significant change in respiratoryrhythmical discharge activity (RRDA), but 7-NI decreased the integral amplitude of burst and inspiratorytime. These results indicate that NO may take part in the inspiratory off-switching mechanism and that it al-so modulates the amplitude of respiratory-related bursts.