乙酰胆碱对大鼠头端延髓腹外侧区前交感神经元放电的作用

Effect of acetylcholine on the discharge of presympathetic neurons of the rostral ventrolateral medulla of rats

实验采用细胞外记录和微电泳等电生理方法 ,研究乙酰胆碱 (ACh)对氨基甲酸乙酯麻醉的大鼠头端延髓腹外侧区 (RVLM)前交感神经元放电频率的影响。在RVLM共记录到 35个前交感神经元 ,微电泳ACh能增加其放电 (P <0 0 5 ) ,并且具有剂量依赖性。其中 2 2个神经元微电泳M型胆碱受体阻断剂阿托品 (ATR)后能明显降低前交感神经元的基础放电 (P <0 0 5 )和完全阻断ACh引起的神经元兴奋作用 ;分别向其余 7和 6个单位微电泳筒箭毒 (AChN1和N2 型受体阻断剂 )或六烃季铵 (AChN1型受体阻断剂 )后均不能影响神经元的基础放电和ACh引起的神经元兴奋作用。结果提示 ,RVLM前交感神经元存在以M型受体介导的胆碱能纤维的紧张性兴奋投射。

Effect of acetylcholine (ACh) on presympathetic neurons of the rostral ventrolateral medulla (RVLM) was studied by extracellular recording technique and microiontophoresis in urethane anaesthetized rats. Spontaneous discharges of 35 presympathetic neurons of RVLM were recorded. All the neurons showed increased discharge by microiontophoresis of ACh dose dependently with the increase of iontophoretic current. In 22 units microiontophoresis of atropine decreased the baseline discharge rate and completely blocked the excitatory effect of ACh on these neurons, while in the remaining 7 and 6 neurons microiontophoresis of d tubocurarine (d TC) and hexamethonium (C 6) respectively had no effect and did not block the action of ACh. The above finding suggests that presympathetic neurons of RVLM receive a tonic excitatory cholinergic input mediated by M receptors.[WT5HZ]