Articles: anesthetics.
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The interaction of four inhalational anesthetics (sevoflurane, isoflurane, enflurane and halothane) with pancuronium and vecuronium and also their prejunctional actions at the neuromuscular junction were quantitatively studied using rat phrenic nerve-hemidiaphragm preparations. To investigate the prejunctional effects of inhalational anesthetics, a train-of-four ratio (T4/T1) and the tetanus ratio (the ratio of the final response to the initial response during tetanus) were evaluated. All four inhalational anesthetics markedly potentiated the neuromuscular blockade of twitch response caused by either pancuronium or vecuronium with halothane and enflurane being the most potent both on a % concentration basis and on a MAC (minimum alveolar concentration) basis. ⋯ Sevoflurane had little effect on the tetanus ratio, whereas 1 and 2% isoflurane and 1, 2 and 3% enflurane increased the tetanus ratio and 5% halothane and 5% enflurane significantly reduced the tetanus ratio. Halothane and enflurane had the most potent depressant action of the four inhalational anesthetics both on the % concentration basis and on the MAC basis. These results indicate that the main site of action of inhalational anesthetics is a postjunctional site at the neuromuscular junction and that they do not seem to act on prejunctional sites at the concentrations used in clinical situations.
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The potential mutagenic activity of three carbamate derivatives with local anaesthetic activity was investigated. Genotoxic activity was observed after application of Carbisocaine on Euglena gracilis, whereas no activity was detected by Carbisocaine, Heptacaine and Pentacaine on Salmonella typhimurium, Escherichia coli and Drosophila melanogaster.
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Tijdschr Diergeneesk · Jul 1990
Comparative Study[Intramuscularly administered non-opiate anesthesia in dogs. A report on the use of ketamine/xylazine, tiletamine/zolazepam, ketamine/midazolam and metomidine].
In the present paper, findings on the use of ketamine/xylazine, ketamine/midazolam, tiletamine/zolazepam, and medetomidine following intramuscular injection in dogs are reported. The combined use of ketamine/xylazine induced anaesthesia, the duration of which was thirty minutes. Untoward side-effects were not observed. ⋯ Neither the combination ketamine/midazolam nor medetomidine induced a surgical level of anaesthesia. Post-anesthetic muscle spasms were a frequently observed side-effect when the combination ketamine/midazolam was administered. The use of medetomidine resulted in a qualitatively satisfactory and prolonged sedation.
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We examined the effect of enflurane on diaphragmatic contractility in six anesthetized mechanically ventilated dogs. The diaphragmatic force was assessed from transdiaphragmatic pressure (Pdi) developed at functional residual capacity against an occluded airway during cervical phrenic nerve stimulation. Pdi-stimulus frequency relationship was compared at three levels of anesthesia, namely 1, 1.5, and 2 MAC (minimum alveolar concentration) of enflurane. ⋯ Pdi of 20 Hz stimulation was significantly decreased at 2 MAC as compared to those at 1 and 1.5 MAC. We conclude that enflurane decreases contractility of the diaphragm mainly through impairment of the neuromuscular transmission and/or membrane excitability. Part of its effects is, however, probably related to the impairment of excitation-contraction coupling, as suggested by the depression of Pdi at 2 MAC in response to 20 Hz stimulation.