title: Effects of isoflurane on the actions of neuromuscular blockers on the muscle nicotine acetylcholine receptors.
abstract: In this study, we tested the hypothesis that volatile anesthetic enhancement of muscle relaxation is the result of combined drug effects on the nicotinic acetylcholine receptors. The poly A m RNA from muscle by isolation were microinjected into Xenopus oocytes for receptor expression. Concentration-effect curves for the inhibition of Ach-induced currents were established for vecuronium, rocuranium, and isoflurane. Subsequently, inhibitory effects of NDMRs were studied in the presence of the isoflurane at a concentration equivalent to half the concentration producing a 50% inhibition alone. All tested drugs produced rapid and readily reversible concentration-dependent inhibition. The 50% inhibitory concentration values were 889 micromol/L (95% CI: 711-1214 micromol). 33.4 micromol (95% CI: 27.1-41.7 nmol) and 9.2 nmol (95% CI: 7.9-12.3 nmol) for isoflurane. rocuranium and vecuronium, respectively. Coapplication of isoflurane significantly enhanced the inhibitory effects of rocuranium and vecuronium, and it was especially so at low concentration of NMDRs. Isoflurane increases the potency of NDMRs, possibly by enhancing antagonist affinity at the receptor site.
authors.affiliation: Department of Anesthesiology, Union Hospital, Tongji Medical College. Huazhong University of Science and Technology, Wuhan 430022, China.
authors.forename: Chuanxiang
authors.initials: C
authors.lastname: Li
authors.forename: Shanglong
authors.initials: S
authors.lastname: Yao
authors.forename: Hui
authors.initials: H
authors.lastname: Nie
authors.forename: Bin
authors.initials: B
authors.lastname: Lü
mesh_terms: D000732:Androstanols / Q000494:pharmacology*; D018685:Anesthetics, Inhalation / Q000494:pharmacology; D000818:Animals; D004357:Drug Synergism; D005260:Female; D007530:Isoflurane / Q000494:pharmacology*; D009466:Neuromuscular Blocking Agents / Q000494:pharmacology*; D009469:Neuromuscular Junction / Q000187:drug effects; D003473:Neuromuscular Nondepolarizing Agents / Q000494:pharmacology*; D009865:Oocytes; D011978:Receptors, Nicotinic / Q000187:drug effects*; D000077123:Rocuronium; D014673:Vecuronium Bromide / Q000494:pharmacology; D014982:Xenopus laevis
chemical_list: D000732:Androstanols; D018685:Anesthetics, Inhalation; D009466:Neuromuscular Blocking Agents; D003473:Neuromuscular Nondepolarizing Agents; D011978:Receptors, Nicotinic; D014673:Vecuronium Bromide; D007530:Isoflurane; D000077123:Rocuronium