股动脉注射琥珀胆碱诱发肌梭传入对延髓呼吸相关神经元活动的影响

目的　观察肌梭传入对延髓呼吸相关神经元自发放电的影响 ,从呼吸中枢的途径探明肌梭传入是否对呼吸运动具有反射性调节作用。方法　在氨基甲酸乙酯麻醉、断双侧颈迷走神经、肌松、人工呼吸的家兔上 ,观察了股动脉注射琥珀胆碱 (Sch)诱发肌梭兴奋对延髓呼吸相关神经元自发放电的影响。用双极银丝电极记录膈神经传出放电 ,用玻璃微电极细胞外记录延髓呼吸相关神经元单位放电 ,根据神经元放电和膈神经放电的时相关系来确定神经元的性质。记录到的单位放电信号输入示波器显示 ,并输入计算机处理 ,绘出序列密度直方图 ,直接测量并打印图形与数据 ;同时与膈神经放电同步照像。结果　 (1 )股动脉注射 Sch可明显兴奋延髓吸气神经元而抑制呼气神经元的放电活动。在 56个吸气神经元中 ,呈兴奋反应的 37个 ,抑制反应的 1 1个 ,双相反应的 2个 ,其余 6个无明显反应。在 1 7个呼气神经元中 ,呈兴奋反应的 4个 ,抑制反应的 1 0个 ,双相反应的 1个 ,其余 2个无明显反应。(2 ) Sch对吸气神经元的兴奋作用 ,一般在给药后 1～2 min即可达高峰 ;而对呼气神经元的抑制作用则发生较晚 ,一般在给药后 2～ 3min达高峰。 (3)肌注布比卡因破坏肌梭后可明显降低 Sch对延髓呼吸相关神经元的影响。较正常侧相比 ,肌注布比卡因侧肢股

Effects of muscle spindle afferents invoked by intraarterial injection of succinylcholine on discharges of medullary respiratory neurons

Objective Through studying the effects of muscle spindles on discharges of medullary respiratory neurons, to ascertain whether muscle spindle afferents had the regulating effects on respiratory movement by ways of the respiratory center.Methods In urethane anesthetized, vagotomized, paralyzed, and artificially ventilated rabbits, the effects of muscle spindle afferents invoked by intraarterial injection Succinylcholine(Sch) on discharges of medullary respiratory neurons have been assessed .The phrenic nerve discharges were recorded by biopolar silver electrode, and the discharges of respiratory neurons were recorded by extracellular glass microelectrode,so the types of neurons were determined by the phasic relationship between the discharges of respiratory neurons and phrenic nerve efferents.The discharges of respiratory units were showed on oscilloscope and their histograms were drawed by computer;In the mean time, the discharges of neurons and phrenic nerves were photographed synchronously.Results ①Most of inspiratory neurons(37/56) in the medulla were excited and most of expiratory neurons(10/17) were inhibited by intraarterial injection of Sch;②The excited climaxof inspiratory neurons was usually at 1~2min after the injection of Sch, and the inhibited climax of expiratory neurons was usually at 2~3min after the injection of Sch;③The effects of Sch on discharges of respiratory neurons were significantly redcuced by intra muscular application of bupivacaine to destroy the muscle spindles.The augmental rate of discharges of inspiratory neurons after Sch was reduced from (56 23±14 45)% to (21 94±1 21)% on the bupivacaine applicated limb compared with the normal limb.Conclusion The results suggest that the activities of muscle spindle afferents play an important role in modulation of respiration.