title: Antagonism of suxamethonium-induced jaw muscle contracture in rats.
abstract: Masseter muscle rigidity (MMR) induced during general anaesthesia by suxamethonium is a clinical problem that may interfere with tracheal intubation. We have investigated the relation between twitch tension and contracture response to suxamethonium in rats. Rats were anaesthetized with 1% halothane (1.35 MAC). Jaw muscle temperature was maintained at either 37 or 41 degrees C while rectal temperature was kept at 37 degrees C by radiant heat. Twitch tension was produced by nerve stimulation at 0.2 Hz. Rats were pretreated with either a low dose of vecuronium (0.03 mg kg-1) or dantrolene (0.8 mg kg-1). Thereafter suxamethonium 750 micrograms kg-1 was administrated i.v. Low-dose vecuronium pretreatment significantly (90%) decreased suxamethonium-induced jaw muscle contracture (JMC) with minimal (3%) twitch block during local hyperthermia. Low-dose dantrolene pretreatment also reduced JMC (81% at 37 degrees C and 82% at 41 degrees C) while decreasing twitch by 30% at 37 degrees C and 31% at 41 degrees C. Both vecuronium and dantrolene at doses that minimally depressed the twitch response antagonized suxamethonium-induced JMC. We speculate that pretreatment with low-dose vecuronium decreases suxamethonium-induced MMR clinically.
authors.affiliation: Department of Anesthesiology, Medical College of Pennsylvania, Philadelphia 19102, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Shi
authors.forename: R J
authors.initials: RJ
authors.lastname: Storella
authors.forename: M M
authors.initials: MM
authors.lastname: Keykhah
authors.forename: H
authors.initials: H
authors.lastname: Rosenberg
mesh_terms: D000818:Animals; D003620:Dantrolene / Q000627:therapeutic use; D008297:Male; D008305:Malignant Hyperthermia / Q000150:complications; D008406:Masseter Muscle / Q000187:drug effects*; D009125:Muscle Relaxants, Central / Q000627:therapeutic use; D009127:Muscle Rigidity / Q000209:etiology / Q000517:prevention & control*; D009467:Neuromuscular Depolarizing Agents / Q000037:antagonists & inhibitors* / Q000633:toxicity; D003473:Neuromuscular Nondepolarizing Agents / Q000627:therapeutic use; D051381:Rats; D011920:Rats, Inbred WF; D013390:Succinylcholine / Q000037:antagonists & inhibitors* / Q000633:toxicity; D014673:Vecuronium Bromide / Q000627:therapeutic use
chemical_list: D009125:Muscle Relaxants, Central; D009467:Neuromuscular Depolarizing Agents; D003473:Neuromuscular Nondepolarizing Agents; D014673:Vecuronium Bromide; D003620:Dantrolene; D013390:Succinylcholine