Modification by ketamine on the neuromuscular actions of magnesium, vecuronium, pancuronium and alpha-bungarotoxin in the primate

Abstract

The neuromuscular effects of ketamine, at cumulative doses of 2.5 and 10 mg · kg-1 iv, were studied by electromyographically quantifying the thumb response evoked by ulnar nerve stimulation in 25 monkeys anaesthetized with pentobarbital-N2O-O2. Ketamine alone at these doses had no neuromuscular effects. When the EMG response was maintained at 50% of control by a continuous infusion of magnesium, vecuronium, or pancuronium, ketamine depressed the responses by an additional 13 ± 3%, 34 ± 7% and 32.5 ± 3.3% (mean ± SEM), respectively, at the highest dose, P < 0.05. In contrast, ketamine had no effect on the neuromuscular block produced by incremental doses of alphabungarotoxin. These results indicate that ketamine does not act on the postjunctional acetylcholine receptor. It plays a secondary role in neuromuscular block, possibly by prejunctional or postjunctional effects independent of receptor occupation. © 1992 Canadian Anesthesiologists.