大鼠CVLM中NMDA和非NMDA受体在介导动脉压力感受器反射中的作用

在氨基甲酸乙酯麻醉、制动的大鼠 ,研究尾端延髓腹外侧区 (CVLM)中 NMDA和非 NMDA受体在介导动脉压力感受器反射 (ABR)中的作用。双侧 CVLM微量注射选择性 NMDA受体拮抗剂氯胺酮 (50mmol/L ,1 0 0 nl)或非 NMDA受体拮抗剂 kynurenic acid(KYA,50 mmol/L ,1 0 0 nl)后平均动脉压 (MAP)和心率 (HR)均明显升高 (P<0 .0 5) ,同时观察到 CVLM微量注射氯胺酮或 KYA后电刺激主动脉神经(AN)导致的血压下降比对照有明显的减少 ,双侧 CVLM微量注射氯胺酮和 KYA的混合物 (均为 50mmol/L,50 nl)后能完全阻断电刺激 AN后导致的降压反应。本研究结果提示 CVLM中 NMDA和非 NM-DA受体在紧张性维持交感神经的兴奋活动和介导 ABR中起十分重要的作用

Role of NMDA and non-NMDA receptors on mediating the arterial baroreceptor reflex in rat CVLM

The role of N Methyl D Aspartate (NMDA) and non NMDA receptors within the caudal ventrolateral medulla (CVLM) on mediating the arterial baroreceptor reflexes (ABR) were studied in urethane anaesthetized and paralyzed adult rats.Both mean arterial pressure (MAP) and heart rate(HR) were increased by bilateral microinjection of either ketamine(a selective NMDA receptor antagonist,50 mmol/L,100nl) or kynurenic acid (KYA,a non NMDA receptor antagonist,50 mmol/L, 100 nl) into the CVLM.The depressor response evoked by electrostimulation of aortic nerve(AN) was partially abolished after bilateral microinjection of either ketamine or KYA alone into the CVLM.Bilateral microinjection of mixture of ketamine and KYA(50 mmol/L and 50 nl, each) into the CVLM caused the complete elimination of the hypotension evoked by AN stimulation. These results demonstrated that both NMDA and non NMDA receptors in the CVLM played an important role in tonically maintaining the sympathetic cardiovascular excitation and mediating the ABR.