Abstract
PURPOSE: To evaluate in vitro lidocaine and racemic bupivacaine effects in neuromuscular transmission and in neuromuscular blockade produced by rocuronium. METHODS: Rats were distributed in 5 groups (n = 5) in agreement with the studied drugs: lidocaine, racemic bupivacaine, rocuronium, separately (Groups I, II, III); rocuronium in preparations exposed to local anesthetics (Groups IV, V). The concentrations used were: 20 µg/mL, 5 µg/mL and 4 µg/mL, for lidocaine, bupivacaine and rocuronium, respectively. It was evaluated: 1) amplitude of diaphragm muscle response to indirect stimulation, before and 60 minutes after separately addition of lidocaine, racemic bupivacaine and rocuronium and the association of local anesthetics - rocuronium; 2) membrane potentials (MP) and miniature end-plate potentials (MEPP). RESULTS: Lidocaine and bupivacaine separately didn't alter the amplitude of muscle response and MP. In preparations previously exposed to lidocaine and racemic bupivacaine, the rocuronium blockade was significantly larger (90.10 ± 9.15% and 100%, respectively), in relation to the produced by rocuronium separately (73.12 ± 9.89%). Lidocaine caused an increase in the frequency of MEPP, being followed by blockade; racemic bupivacaine produced decrease being followed by blockade. CONCLUSIONS: Local anesthetics potentiated the blockade caused by rocuronium. The alterations of MEPP identify presynaptic action.
Highlights
Clinical assays describe that local anesthetics by nerve-diaphragm preparation for the study of local anesthetics efperidural route, routine used in association to general anesthesia, fects in miniature end-plate potentials and in membrane potentials
Can interact and potentiate the effects of neuromuscular blocking It was evaluated: 1) the amplitude of diaphragm muscle responses agents[2,3,7,12], interaction observed in experimental studies9,11. to indirect stimulation, before and 60 minutes after the addition of these effects have been experimentally lidocaine, racemic bupivacaine and rocuronium separately; 2) amdemonstrated in isolated preparations and clinical assays, the plitude of diaphragm muscle responses to indirect stimulation, beinfluence in neuromuscular transmission and in neuromuscular fore and 60 minutes after rocuronium addition in preparations preblockade produced by competitive neuromuscular blocking agents viously exposed to lidocaine and racemic bupivacaine; 3) the memit is still objective of little investigation1-3, . 6-9,11-12,14 brane potentials (MP) and miniature end-plate potentials (MEPP)
The results obtained in this work show that in rat phrenic nerve-diaphragm preparation, lidocaine and racemic bupivacaine in the employed concentrations, and, separately administered don’t commit neuromuscular transmission, the blockade produced by rocuronium in preparations previously exposed to the different local anesthetics was significantly larger than observed in preparations not exposed to local anesthetics
Summary
There are evidences that pharmacokinetic and pharmacodynamic properties of neuromuscular blocking agents, drugs commonly used in general anesthesia, can be modified by factors as acid-basic state, temperature, monitoring, certain diseases (burns, superior and inferior motor neuron disease) and drugs administered by different routes[1,2,3,4,5,6,7,8,9,10,11,12,13]. Can interact and potentiate the effects of neuromuscular blocking It was evaluated: 1) the amplitude of diaphragm muscle responses agents[2,3,7,12], interaction observed in experimental studies. To indirect stimulation, before and 60 minutes after the addition of these effects have been experimentally lidocaine, racemic bupivacaine and rocuronium separately; 2) amdemonstrated in isolated preparations and clinical assays, the plitude of diaphragm muscle responses to indirect stimulation, beinfluence in neuromuscular transmission and in neuromuscular fore and 60 minutes after rocuronium addition in preparations preblockade produced by competitive neuromuscular blocking agents viously exposed to lidocaine and racemic bupivacaine; 3) the memit is still objective of little investigation1-3, .
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