大鼠延髓腹外侧区在可乐定心血管效应中的作用

目的：探讨大鼠延髓腹外侧区（VLM）在介导可乐定心血管效应中的作用。方法：氨基甲酸乙酯麻醉SD大鼠，应用微量注射和细胞外记录等方法观察尾端延髓腹外侧区（CVLM）和头端延髓腹外侧区（RVLM）内局部给予可乐定导致的心血管活动变化。结果：单侧CVLM微量注射可乐定（5nmol/100nl,n=10)不仅能明显升主动脉血压（AP）和增加心率（HR）（P＜0．01），而且能增加同侧RVLM压力敏感性神经元（n=80)的放电频率（P＜0．01），而单侧RVLM微量注射可乐定（5nmol/100nl,n=9)，明显降低AP和HR（P＜0．01）。结论：RVLM和CVLM在介导可乐定的心血管效应中具有不同的作用。

Roles of the ventrolateral medulla in clonidine-induced cardiovascular effects of rats

Objective:To investigate the roles of the ventrolateral medulla (VLM) in mediating the cardiovascular response of clonidine.Methods: In urethane anesthetized SD rats,the responses of locally administrated clonidine within the caudal ventrolateral medulla (CVLM) and the rostral ventrolateral medulla (RVLM) to the cardiovascular activities were observed by methods of microinjection and extracellular recording.Results: Unilateral microinjection of clonidine (5 nmol/100 nl) into the CVLM not only produced significant ( P <0.01, n =10) increases in both arterial blood pressure (AP) and heart rate (HR),but also significantly increased the firing rate of the ipsilateral RVLM barosensitive neurons ( P <0.01, n =8).In addition,unilateral microinjection of clonidine (5 nmol/100 nl, n =9) into the RVLM significantly decreased in both AP and HR ( P <0.01).Conclusion: CVLM and RVLM might play different roles in the cardiovascular effects of clonidine.