title: Effect of rocuronium on the level and mode of pre-synaptic acetylcholine release by facial and somatic nerves, and changes following facial nerve injury in rabbits.
abstract: Muscles innervated by the facial nerve show differential sensitivities to muscle relaxants than muscles innervated by somatic nerves. The evoked electromyography (EEMG) response is also proportionally reduced after facial nerve injury. This forms the theoretical basis for proper utilization of muscle relaxants to balance EEMG monitoring and immobility under general anesthesia. (1) To observe the relationships between the level and mode of acetylcholine (ACh) release and the duration of facial nerve injury, and the influence of rocuronium in an in vitro rabbit model. (2) To explore the pre-synaptic mechanisms of discrepant responses to a muscle relaxant. Quantal and non-quantal ACh release were measured by using intracellular microelectrode recording in the orbicularis oris 1 to 42 days after graded facial nerve injury and in the gastrocnemius with/without rocuronium. Quantal ACh release was significantly decreased by rocuronium in the orbicularis oris and gastrocnemius, but significantly more so in gastrocnemius. Quantal release was reduced after facial nerve injury, which was significantly correlated with the severity of nerve injury in the absence but not in the presence of rocuronium. Non-quantal ACh release was reduced after facial nerve injury, with many relationships observed depending on the extent of the injury. The extent of inhibition of non-quantal release by rocuronium correlated with the grade of facial nerve injury. These findings may explain why EEMG amplitude might be diminished after acute facial nerve injury but relatively preserved after chronic injury and differential responses in sensitivity to rocuronium.
authors.affiliation: Department of Anesthesiology, Eye and ENT hospital of Fudan University Shanghai 200031, China.
authors.forename: Jinghua
authors.initials: J
authors.lastname: Tan
authors.affiliation: Department of Anesthesiology, Eye and ENT hospital of Fudan University Shanghai 200031, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Xu
authors.affiliation: Shanghai First People's Hospital, Shanghai Jiao Tong University Shanghai 200080, China.
authors.forename: Yian
authors.initials: Y
authors.lastname: Xing
authors.affiliation: Shanghai First People's Hospital, Shanghai Jiao Tong University Shanghai 200080, China.
authors.forename: Lianhua
authors.initials: L
authors.lastname: Chen
authors.affiliation: Shanghai First People's Hospital, Shanghai Jiao Tong University Shanghai 200080, China.
authors.forename: Shitong
authors.initials: S
authors.lastname: Li
mesh_terms: D000109:Acetylcholine / Q000378:metabolism*; D000732:Androstanols / Q000494:pharmacology*; D000818:Animals; D004195:Disease Models, Animal; D004576:Electromyography; D005154:Facial Nerve / Q000187:drug effects / Q000378:metabolism; D020220:Facial Nerve Injuries / Q000378:metabolism*; D008297:Male; D008839:Microelectrodes; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000294:innervation / Q000502:physiology; D009469:Neuromuscular Junction / Q000187:drug effects; D003473:Neuromuscular Nondepolarizing Agents / Q000494:pharmacology*; D011817:Rabbits; D000077123:Rocuronium; D013979:Tibial Nerve / Q000187:drug effects / Q000378:metabolism
chemical_list: D000732:Androstanols; D003473:Neuromuscular Nondepolarizing Agents; D000109:Acetylcholine; D000077123:Rocuronium
keywords: Rocuronium; acetylcholine; facial nerve; non-quantal release; pre-synaptic; quantal release