NMDA与非NMDA受体激动剂对新生大鼠延髓脑片呼吸节律性放电的作用

目的：探讨N－甲基－D－天门冬氨酸（NMDA）和非NMDA类受体在基本呼吸节律发生和调节中的可能作用。方法：以改良的Kerb's液灌流新生SD大鼠离体延髓脑片,记录片与之相连的舌下神经的呼吸节律性放电活动（respiratory rhythmical discharge activity,RRDA),在灌流中给予兴奋性氨式酸类递质及相应的拮抗剂,观察其对RRDA的影响。结果：使用非NMDA受体激动剂海人酸（KA）后,可见呼吸周期及呼吸时间有所延长,NMDA受体激动剂NMDA对呼吸活动则没有明显影响;相应的拮抗剂6－氰基－7－硝基喹恶啉土卫四（DNAX）和2－氨基酸戊酸（AP5）均可使放电频率和积分幅值明显降低,吸气时间显著缩短,但DNQX同时可致呼吸周期和呼气时间明显缩短。结论：在哺乳动物基本呼吸节律的产生和调节中,NMDA类受体主要对呼吸活动的强度产生调节作用;而非NMDA类受体不仅可以影响呼吸的强度,同时对呼吸的频率也发挥调节作用。

Effects of NMDA and non-NMDA agonists on the respiratory rhythmical discharge of the hypoglossal nerve in the medullary slice from neonatal rats

Aim: To study the possible role of the NMDA and non NMDA receptor on the generation and modulation of basic respiratory rhythm. Methods: Experiments were performed on the medullary slices isolated from the neonatal rats. Respiratory rhythmical discharge activity (RRDA) of the hypoglossal nerve was recorded by suction electrode,then the effects of the excitatory amino acids and its antagonists on the RRDA were investigated by adding these drugs into the perfused modified Kreb's solution. Results: After applying the non-NMDA receptor agonist KA, it was found that the respiratory circle and the expiratory time were lightly lengthened,but the NMDA receptor agonist NMDA had no effect on the RRDA.Both of the mutual antagonist DNQX and AP 5 remarkably decreased the discharge frequency and the integral amplitude, accompanied by the shortening of the inspiratory time,DNQX simultaneously shortened the respiratory circle and the expiratory time. Conclusion:During the generation and modulation of the mammalian respiratory rhythm, NMDA receptor may mainly play a role in the amplitude of the respiratory activity, the non NMDA receptor can not only affect the amplitude of the respiratory discharge also modulate the frequency of the respiratory rhythm.