Different sensitivities to rocuronium of the neuromuscular junctions innervated by normal/damaged facial nerves and somatic nerve in rats： the role of the presynaptic acetylcholine quantal release  

作　　者：CHEN Jun-liang LI Shao-qin CHI Fang-lu CHEN Lian-hua LI Shi-tong 

机构地区：[1]Department of Anesthesiology , Department of Otolaryngology , Eye Ear Nose and Throat Hospital, Fudan University, Shanghai 200031, China [2]Department of Anesthesiology, First People＇s Hospital, Shanghai Jiao Tong University, Shanghai 200080, China

出　　处：《Chinese Medical Journal》2012年第10期1747-1752,共6页中华医学杂志（英文版）

基　　金：The study was supported by a grant from tt（e National Natural Science Foundation of China （No. 30872428）.

摘　　要：Background Muscles present different responses to muscle relaxants, a mechanism of importance in surgeries requiring facial nerve evoked electromyography under general anaesthesia. The non-depolarizing muscle relaxants have multiple reaction formats in the neuromuscular junction, in which pre-synaptic quantal release of acetylcholine was one of the important mechanisms. This study was to compare the pre-synaptic quantal release of acetylcholine from the neuromuscular junctions innervated by normal/damaged facial nerves and somatic nerve under the effect of rocuronium in rats in vitro. Methods Acute right-sided facial nerve injury was induced by nerve crush axotomies. Both sided facial nerve connected orbicularis oris strips and tibial nerve connected gastrocnemius strips were isolated to measure endplate potentials （EPP） and miniature endplate potentials （MEPP） using an intracellular microelectrode gauge under different rocuronium concentrations. Then, the pre-synaptic quantal releases of acetylcholine were calculated by the ratios of the EPPs and the MEPPs, and compared among the damaged or normal facial nerve innervated orbicularis oris and tibial nerve innervated gastrocnemius. Results The EPP/MEPP ratios of the three neuromuscular junctions decreased in a dose dependent manner with the increase of the rocuronium concentration. With the concentrations of rocuronium being 5 pg/ml, 7.5 IJg/ml and 10 pg/ml, the decrease of the EPP/MEPP ratio in the damaged facial nerve group was greater than that in the normal facial nerve group. The decrease in the somatic nerve group was the biggest, with significant differences. Conclusions Rocuronium presented different levels of inhibition on the pre-synaptic quantal release of acetylcholine in the three groups of neuromuscular junctions. The levels of the inhibition showed the following sequence： somatic nerve 〉 damaged facial nerve 〉 normal facial nerve. The difference may be one of the reasons causing the different sensitivities to rocuronium among the musclBackground Muscles present different responses to muscle relaxants, a mechanism of importance in surgeries requiring facial nerve evoked electromyography under general anaesthesia. The non-depolarizing muscle relaxants have multiple reaction formats in the neuromuscular junction, in which pre-synaptic quantal release of acetylcholine was one of the important mechanisms. This study was to compare the pre-synaptic quantal release of acetylcholine from the neuromuscular junctions innervated by normal/damaged facial nerves and somatic nerve under the effect of rocuronium in rats in vitro. Methods Acute right-sided facial nerve injury was induced by nerve crush axotomies. Both sided facial nerve connected orbicularis oris strips and tibial nerve connected gastrocnemius strips were isolated to measure endplate potentials （EPP） and miniature endplate potentials （MEPP） using an intracellular microelectrode gauge under different rocuronium concentrations. Then, the pre-synaptic quantal releases of acetylcholine were calculated by the ratios of the EPPs and the MEPPs, and compared among the damaged or normal facial nerve innervated orbicularis oris and tibial nerve innervated gastrocnemius. Results The EPP/MEPP ratios of the three neuromuscular junctions decreased in a dose dependent manner with the increase of the rocuronium concentration. With the concentrations of rocuronium being 5 pg/ml, 7.5 IJg/ml and 10 pg/ml, the decrease of the EPP/MEPP ratio in the damaged facial nerve group was greater than that in the normal facial nerve group. The decrease in the somatic nerve group was the biggest, with significant differences. Conclusions Rocuronium presented different levels of inhibition on the pre-synaptic quantal release of acetylcholine in the three groups of neuromuscular junctions. The levels of the inhibition showed the following sequence： somatic nerve 〉 damaged facial nerve 〉 normal facial nerve. The difference may be one of the reasons causing the different sensitivities to rocuronium among the muscl

关 键 词：rocuronium  pre-synaptic acetylcholine  quantal release facial nerve 

分 类 号：Q959.53[生物学—动物学] Q422