Effects of Pseudocholinesterase, Anticholinesterase, and 4-Aminopyridine to the Mivacurium-induced Neuromuscular Block on Rat Diaphragm / 대한마취과학회지

ABSTRACT

BACKGROUND: Prolongation of the neuromuscular block of mivacurium can occur when there is a genetic deficiency of the enzyme or in the presence of anticholinesterase (AntiChE) which inhibit the activity of the enzyme. The aim of this study was to determine the efficacies of cholinesterase, AntiChE (neostigmine, pyridostigmine), and 4-aminopyridine in reversing mivacurium block, using the phrenic nerve-diaphragm preparation of a rat. METHODS: Forty-eight Sprague-Dawley rats (200~300 g) were anesthetized with peritoneal injection of 2.5% thiopental 5~10 ml. After a stable twitch and train-of-four responses were established for at least 30 minutes in each preparation, incremental dose of mivacurium was added to obtain 90~95% inhibition of control twitch height. The effects of 0.1 and 1.0 u/ml of horse pseudocholinesterase (pChE, Sigma), 0.1 and 1.0 g/ml of neostigmine, 0.2 and 2.0 g/ml of pyridostigmine, and 1.6, 16 g/ml of 4-aminopyridine (P.B.I) on reversal of mivacurium block were tested. The effects of 0.1 g/ml of neostigmine, or 0.2 g/ml of pyridostigmine with and without 0.1 or 1.0 u/ml of pChE following mivacurium were also tested. RESULTS: In reversing mivacurium block, single twitch and TOF ratios were recovered completely with pChE but not with antiChEs or 4-aminopyridine (p<0.05). Second set of experiments showed that antiChE mixed with pChE had a tendency to recover faster (p<0.05). The comparable recovery patterns of pChE 0.1u/ml alone and neostigmine 0.1 g/ml with pChE 0.1u/ml in our study, indicated that neostigmine would prolong the mivacurium block especially in the presence of hereditary or acquired defects of pChE activity. CONCLUSION: The authors conclude that pChE 1.0 u/ml with and without antiChE were equally effective in reversing neuromuscular block of mivacurium. If these results can be extrapolated to human, it is unlikely that mivacurium block is potentiated by antiChE that may slow its metabolism.