Anesthesiology
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This study was performed to compare the effects of three anticholinesterases on rates of recovery from pancuronium-induced neuromuscular blockade. Pancuronium (3 mg/70 kg) was antagonized during nitrous oxide-oxygen-halothane anesthesia, in man, with neostigmine (2.5 or 5.0 mg/70 kg), pyridostigmine (10 or 20 mg/70 kg), or edrophonium (50 or 100 mg/70 kg). Reversal was attempted at 10 per cent spontaneous recovery of muscle twitch, which was measured by use of train-of-four stimulation. ⋯ Thirty minutes after reversal there was no significant difference in recoveries among the drugs tested, and T4 exceeded 70 per cent for all patients. It is concluded that, under the conditions of this study, neostigmine, pyridostigmine, and edrophonium induce sustained antagonism of pancuronium-induced neuromuscular blockade. The antagonism produced by large doses of edrophonium is faster than that produced by neostigmine or pyridostigmine.
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Modification of ryanodine toxicity by dantrolene and halothane in a model of malignant hyperthermia.
Ryanodine toxicity in animals has been suggested to constitute a model of malignant hyperthermia. Dantrolene is known to block the development of malignant hyperthermia triggered by halothane in susceptible swine. The authors studied the influences of dantrolene and halothane on the effects of ryanodine in vitro in isolated rat diaphragm muscle segments, and in vivo in mice, to explore the validity of this model. ⋯ Pretreatment of mice for 48 hours with orally administered dantrolene, followed by injection of ryanodine and then halothane anesthesia, decreased the lethality of ryanodine but did not reduce the number of deaths caused by the subsequent exposure to halothane. That the effects of ryanodine in vitro and in vivo are diminished and potentiated by dantrolene and halothane, respectively, would suggest that the ryanodine toxicity model of malignant hyperthermia may have validity and is worthy of further study. A prediction from this model is that the terminal cisternae of skeletal muscle sarcoplasmic reticulum may be altered in MH.