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Drexler B, Seeger T, Worek F, Thiermann H, Antkowiak B, Grasshoff C. Impact of soman and acetylcholine on the effects of propofol in cultured cortical networks. Toxicol Lett 2020; 322:98-103. [PMID: 31954869 DOI: 10.1016/j.toxlet.2020.01.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 12/20/2019] [Accepted: 01/15/2020] [Indexed: 11/29/2022]
Abstract
Patients intoxicated with organophosphorous compounds may need general anaesthesia to enable mechanical ventilation or for control of epileptiform seizures. It is well known that cholinergic overstimulation attenuates the efficacy of general anaesthetics to reduce spontaneous network activity in the cortex. However, it is not clear how propofol, the most frequently used intravenous anaesthetic today, is affected. Here, we investigated the effects of cholinergic overstimulation induced by soman and acetylcholine on the ability of propofol to depress spontaneous action potential activity in organotypic cortical slices measured by extracellular voltage recordings. Cholinergic overstimulation by co-application of soman and acetylcholine (10 μM each) did not reduce the relative inhibition of propofol (1.0 μM; mean normalized action potential firing rate 0.49 ± 0.06 of control condition, p < 0.001, Wilcoxon signed rank test) but clearly reduced its efficacy. Co-application of atropine (10 nM) did not improve the efficacy. Propofol preserved its relative inhibitory potential but did not produce a degree of neuronal depression which can be expected to assure hypnosis in humans. Since a combination with atropine did not improve its efficacy, an increase in dosage will probably be necessary when propofol is used in victims suffering from organophosphorous intoxication.
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Affiliation(s)
- Berthold Drexler
- Experimental Anesthesiology Section, Department of Anesthesiology and Intensive Care Medicine, Eberhard-Karls-University, Waldhoernlestrasse 22, 72072, Tuebingen, Germany.
| | - Thomas Seeger
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstrasse 11, 80937, Munich, Germany.
| | - Franz Worek
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstrasse 11, 80937, Munich, Germany.
| | - Horst Thiermann
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstrasse 11, 80937, Munich, Germany.
| | - Bernd Antkowiak
- Experimental Anesthesiology Section, Department of Anesthesiology and Intensive Care Medicine, Eberhard-Karls-University, Waldhoernlestrasse 22, 72072, Tuebingen, Germany; Werner Reichardt Center for Integrative Neuroscience, Eberhard-Karls-University, Tuebingen, Germany.
| | - Christian Grasshoff
- Experimental Anesthesiology Section, Department of Anesthesiology and Intensive Care Medicine, Eberhard-Karls-University, Waldhoernlestrasse 22, 72072, Tuebingen, Germany.
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Marquart K, Herbert J, Amend N, Thiermann H, Worek F, Wille T. Effect of cholinergic crisis on the potency of different emergency anaesthesia protocols in soman-poisoned rats. Clin Toxicol (Phila) 2018; 57:343-349. [PMID: 30307341 DOI: 10.1080/15563650.2018.1520241] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
BACKGROUND In a military or terrorist scenario, combination of organophosphorus compounds (OP) poisoning with physical trauma requiring surgical treatment and thus general anaesthesia are possible. Previous in vitro studies showed an altered potency of relevant anaesthetics during cholinergic crisis. Hence, it is not clear, which anaesthetics are suitable to achieve the necessary stage of surgical anaesthesia in OP poisoning. METHODS In the present study, different anaesthetic regimens (ketamine-midazolam, propofol-fentanyl, thiopental-fentanyl), relevant in military emergency medicine, were examined in soman-poisoned rats. Clinical signs and cardiovascular variables were recorded continuously. Blood samples for acetylcholinesterase (AChE) activity were drawn. After euthanasia or death of the animals, brain and diaphragm were collected for cholinesterase assays. RESULTS Propofol-fentanyl and thiopental-fentanyl resulted in surgical anaesthesia throughout the experiments. With ketamine-midazolam, surgical anaesthesia without respiratory impairment could not be achieved in pilot experiments (no soman challenge) and was therefore not included in the study. Soman-poisoned and control animals required a comparable amount of propofol-fentanyl or thiopental-fentanyl. In combination with atropine, significantly less propofol was needed. Survival rate was higher with thiopental compared to propofol. Atropine improved survival in both groups. Blood and tissue AChE activities were strongly inhibited after soman administration with and without atropine treatment. DISCUSSION The current in vivo study did not confirm concerns of altered potency of existing anaesthetic protocols for the application of propofol or thiopental with fentanyl due to soman poisoning. Despite severe cholinergic crisis, sufficient anaesthetic depth could be achieved in all animals. CONCLUSION Further experiments in in vivo models closer to human pharmaco- and toxicokinetics (e.g., swine) are required for confirmation of the initial findings and for improving extrapolation to humans.
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Affiliation(s)
- Katharina Marquart
- a Bundeswehr Institute of Pharmacology and Toxicology , Munich , Germany
| | - Julia Herbert
- a Bundeswehr Institute of Pharmacology and Toxicology , Munich , Germany
| | - Niko Amend
- a Bundeswehr Institute of Pharmacology and Toxicology , Munich , Germany
| | - Horst Thiermann
- a Bundeswehr Institute of Pharmacology and Toxicology , Munich , Germany
| | - Franz Worek
- a Bundeswehr Institute of Pharmacology and Toxicology , Munich , Germany
| | - Timo Wille
- a Bundeswehr Institute of Pharmacology and Toxicology , Munich , Germany
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Drexler B, Seeger T, Worek F, Thiermann H, Antkowiak B, Grasshoff C. Midazolam is effective to reduce cortical network activity in organotypic cultures during severe cholinergic overstimulation with soman. Toxicol Lett 2018; 297:19-23. [PMID: 30165091 DOI: 10.1016/j.toxlet.2018.08.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 08/14/2018] [Accepted: 08/25/2018] [Indexed: 12/13/2022]
Abstract
Intoxication with organophosphorus compounds can result in life-threatening organ dysfunction and refractory seizures. Sedation or hypnosis is essential to facilitate mechanical ventilation and control seizure activity. The range of indications for midazolam includes both hypnosis and seizure control. Since benzodiazepines cause sedation and hypnosis by dampening neuronal activity of the cerebral cortex, we investigated the drug's effect on action potential firing of cortical neurons in brain slices. Extensive cholinergic overstimulation was induced by increasing acetylcholine levels and simultaneously treating the slices with soman to block acetylcholinesterase activity. At control conditions midazolam reduced discharge rates (median/95% confidence interval) from 8.8 (7.0-10.5) Hz (in the absence of midazolam) to 2.2 (1.4-2.9) Hz (10 μM midazolam) and 1.6 (0.9-2.2) Hz (20 μM midazolam). Without midazolam, cholinergic overstimulation significantly enhanced neuronal activity to 13.1 (11.0-15.2) Hz. Midazolam attenuated firing rates during cholinergic overstimulation to 6.5 (4.8-8.2) Hz (10 μM midazolam) and 4.1 (3.3-6.0) Hz (20 μM midazolam), respectively. Thus, high cholinergic tone attenuated the drug's efficacy only moderately. These results suggest that midazolam is worth being tested as a promising drug to induce sedation and hypnosis in patients suffering from severe organophosphorous intoxication.
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Affiliation(s)
- Berthold Drexler
- Experimental Anesthesiology Section, Department of Anesthesiology and Intensive Care Medicine, Eberhard-Karls-University, Waldhoernlestrasse 22, 72072 Tuebingen, Germany.
| | - Thomas Seeger
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstrasse 11, 80937 Munich, Germany.
| | - Franz Worek
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstrasse 11, 80937 Munich, Germany.
| | - Horst Thiermann
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstrasse 11, 80937 Munich, Germany.
| | - Bernd Antkowiak
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstrasse 11, 80937 Munich, Germany; Werner Reichardt Center for Integrative Neuroscience, Eberhard-Karls-University, Tuebingen, Germany.
| | - Christian Grasshoff
- Experimental Anesthesiology Section, Department of Anesthesiology and Intensive Care Medicine, Eberhard-Karls-University, Waldhoernlestrasse 22, 72072 Tuebingen, Germany.
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Whitmore C, Cook AR, Mann T, Price ME, Emery E, Roughley N, Flint D, Stubbs S, Armstrong SJ, Rice H, Tattersall JEH. The efficacy of HI-6 DMS in a sustained infusion against percutaneous VX poisoning in the guinea-pig. Toxicol Lett 2017; 293:207-215. [PMID: 29129798 DOI: 10.1016/j.toxlet.2017.11.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Revised: 11/02/2017] [Accepted: 11/06/2017] [Indexed: 11/29/2022]
Abstract
Post-exposure nerve agent treatment usually includes administration of an oxime, which acts to restore function of the enzyme acetylcholinesterase (AChE). For immediate treatment of military personnel, this is usually administered with an autoinjector device, or devices containing the oxime such as pralidoxime, atropine and diazepam. In addition to the autoinjector, it is likely that personnel exposed to nerve agents, particularly by the percutaneous route, will require further treatment at medical facilities. As such, there is a need to understand the relationship between dose rate, plasma concentration, reactivation of AChE activity and efficacy, to provide supporting evidence for oxime infusions in nerve agent poisoning. Here, it has been demonstrated that intravenous infusion of HI-6, in combination with atropine, is efficacious against a percutaneous VX challenge in the conscious male Dunkin-Hartley guinea-pig. Inclusion of HI-6, in addition to atropine in the treatment, improved survival when compared to atropine alone. Additionally, erythrocyte AChE activity following poisoning was found to be dose dependent, with an increased dose rate of HI-6 (0.48mg/kg/min) resulting in increased AChE activity. As far as we are aware, this is the first study to correlate the pharmacokinetic profile of HI-6 with both its pharmacodynamic action of reactivating nerve agent inhibited AChE and with its efficacy against a persistent nerve agent exposure challenge in the same conscious animal.
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Affiliation(s)
- C Whitmore
- CBR (Chemical, Biological, Radiological), Dstl Porton Down, Salisbury, Wiltshire, SP4 0JQ, United Kingdom.
| | - A R Cook
- CBR (Chemical, Biological, Radiological), Dstl Porton Down, Salisbury, Wiltshire, SP4 0JQ, United Kingdom
| | - T Mann
- CBR (Chemical, Biological, Radiological), Dstl Porton Down, Salisbury, Wiltshire, SP4 0JQ, United Kingdom
| | - M E Price
- CBR (Chemical, Biological, Radiological), Dstl Porton Down, Salisbury, Wiltshire, SP4 0JQ, United Kingdom
| | - E Emery
- CBR (Chemical, Biological, Radiological), Dstl Porton Down, Salisbury, Wiltshire, SP4 0JQ, United Kingdom
| | - N Roughley
- CBR (Chemical, Biological, Radiological), Dstl Porton Down, Salisbury, Wiltshire, SP4 0JQ, United Kingdom
| | - D Flint
- CBR (Chemical, Biological, Radiological), Dstl Porton Down, Salisbury, Wiltshire, SP4 0JQ, United Kingdom
| | - S Stubbs
- CBR (Chemical, Biological, Radiological), Dstl Porton Down, Salisbury, Wiltshire, SP4 0JQ, United Kingdom
| | - S J Armstrong
- CBR (Chemical, Biological, Radiological), Dstl Porton Down, Salisbury, Wiltshire, SP4 0JQ, United Kingdom
| | - H Rice
- CBR (Chemical, Biological, Radiological), Dstl Porton Down, Salisbury, Wiltshire, SP4 0JQ, United Kingdom
| | - J E H Tattersall
- CBR (Chemical, Biological, Radiological), Dstl Porton Down, Salisbury, Wiltshire, SP4 0JQ, United Kingdom
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Weimer I, Worek F, Seeger T, Thiermann H, Grasshoff C, Antkowiak B, Balk M. Anesthetic actions of thiopental remain largely unaffected during cholinergic overstimulation in cultured cortical networks. Toxicol Lett 2016; 244:129-135. [PMID: 26325215 DOI: 10.1016/j.toxlet.2015.08.1106] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Revised: 08/28/2015] [Accepted: 08/28/2015] [Indexed: 10/23/2022]
Abstract
In case of military or terrorist use of organophosphorus (OP) compounds victims are likely to suffer from not only intoxication but physical trauma as well. Appropriate emergency care may therefore include general anesthesia to allow life-saving surgical intervention. Since there is evidence that drug potency and efficacy of several anesthetics are attenuated by high concentrations of acetylcholine in the CNS, this study was designed to evaluate the anesthetic actions of thiopental during cholinergic overstimulation. Making use of organotypic slice cultures derived from the mouse neocortex, drug effects were assessed by extracellular voltage recordings of network activity at basal cholinergic tone and during simulated cholinergic crisis (high cholinergic tone). The latter was achieved by inhibition of acetylcholinesterases via soman and an ambient acetylcholine concentration of 10μM. The induction of cholinergic crisis in vitro increased the network activity of cortical neurons significantly. Surprisingly, differences in network activity between basal and high cholinergic tone became less pronounced with rising concentrations of thiopental and drug potency and efficacy were almost equivalent. These results clearly distinguish thiopental from previously tested general anesthetics and make it a promising candidate for in vivo studies to identify suitable anesthetics for victims of OP intoxication.
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Affiliation(s)
- Isabel Weimer
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstrasse 11, 80937 Munich, Germany; Department of Anaesthesiology, Experimental Anaesthesiology Section, Eberhard-Karls-University, Waldhoernlestrasse 22, 72072 Tuebingen, Germany.
| | - Franz Worek
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstrasse 11, 80937 Munich, Germany
| | - Thomas Seeger
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstrasse 11, 80937 Munich, Germany
| | - Horst Thiermann
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstrasse 11, 80937 Munich, Germany
| | - Christian Grasshoff
- Department of Anaesthesiology, Experimental Anaesthesiology Section, Eberhard-Karls-University, Waldhoernlestrasse 22, 72072 Tuebingen, Germany
| | - Bernd Antkowiak
- Department of Anaesthesiology, Experimental Anaesthesiology Section, Eberhard-Karls-University, Waldhoernlestrasse 22, 72072 Tuebingen, Germany; Werner-Reichardt-Centre for Integrative Neuroscience, Eberhard-Karls-University, 72076 Tuebingen, Germany
| | - Monika Balk
- Department of Anaesthesiology, Experimental Anaesthesiology Section, Eberhard-Karls-University, Waldhoernlestrasse 22, 72072 Tuebingen, Germany
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Drexler B, Zinser S, Seeger T, Thiermann H, Antkowiak B, Grasshoff C. Anaesthetic potency of diazepam is resistant to cholinergic overstimulation. Toxicol Lett 2011; 206:84-8. [PMID: 21699965 DOI: 10.1016/j.toxlet.2011.06.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2011] [Revised: 06/01/2011] [Accepted: 06/06/2011] [Indexed: 11/26/2022]
Abstract
Patients suffering from organophosphorus intoxication are compromised by generalised seizures and respiratory insufficiency, either being potentially lethal. In these patients induction of general anaesthesia to allow artificial ventilation is an important therapeutic option. Previously, it has been demonstrated that cholinergic overstimulation impaired network depressing effects of etomidate and sevoflurane. In this study we tested the impact of cholinergic overstimulation on inhibitory effects of diazepam in organotypic slice cultures of cerebrocortical neurons. Effects of clinically relevant concentrations of diazepam on spontaneous action potential activity were assessed by extracellular action potential recordings under basal cholinergic tone as well as in the presence of acetylcholine (1 μM). Diazepam at anaesthetic concentrations (25-500 μM) impeded spontaneous network activity in a concentration dependent manner (EC₅₀ 80.5±8.0 μM). In the presence of 1 μM acetylcholine the potency of diazepam was not significantly altered (EC₅₀ 83.6±8.4 μM). The results demonstrate that the potency of diazepam to depress neocortical network-excitability is not significantly impaired by cholinergic overstimulation. Diazepam thereby differs from other anaesthetics like etomidate or sevoflurane whose potencies and efficacies were severely attenuated. Hence diazepam might be preferable for induction and maintenance of general anaesthesia in patients suffering from nerve agent intoxication.
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Affiliation(s)
- Berthold Drexler
- Department of Anaesthesiology, Experimental Anaesthesiology Section, Eberhard-Karls-University, Schaffhausenstrasse 113, 72072 Tuebingen, Germany
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Gubert P, Ávila DS, Bridi JC, Saurin S, Lugokenski TH, Villarinho JG, Fachinetto R, Pereira ME, Ferreira J, da Rocha JBT, Soares FAA. Low concentrations of methamidophos do not alter AChE activity but modulate neurotransmitters uptake in hippocampus and striatum in vitro. Life Sci 2011; 88:89-95. [DOI: 10.1016/j.lfs.2010.10.031] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2010] [Revised: 09/25/2010] [Accepted: 10/26/2010] [Indexed: 11/24/2022]
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