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Martyn JAJ, Sparling JL, Bittner EA. Molecular mechanisms of muscular and non-muscular actions of neuromuscular blocking agents in critical illness: a narrative review. Br J Anaesth 2023; 130:39-50. [PMID: 36175185 DOI: 10.1016/j.bja.2022.08.009] [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: 04/11/2022] [Revised: 08/05/2022] [Accepted: 08/08/2022] [Indexed: 01/05/2023] Open
Abstract
Despite frequent use of neuromuscular blocking agents in critical illness, changes in neuromuscular transmission with critical illness are not well appreciated. Recent studies have provided greater insights into the molecular mechanisms for beneficial muscular effects and non-muscular anti-inflammatory properties of neuromuscular blocking agents. This narrative review summarises the normal structure and function of the neuromuscular junction and its transformation to a 'denervation-like' state in critical illness, the underlying cause of aberrant neuromuscular blocking agent pharmacology. We also address the important favourable and adverse consequences and molecular bases for these consequences during neuromuscular blocking agent use in critical illness. This review, therefore, provides an enhanced understanding of clinical therapeutic effects and novel pathways for the salutary and aberrant effects of neuromuscular blocking agents when used during acquired pathologic states of critical illness.
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Affiliation(s)
- J A Jeevendra Martyn
- Department of Anesthesiology, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA; Shriners Hospitals for Children, Boston, MA, USA; Harvard Medical School, Boston, MA, USA
| | - Jamie L Sparling
- Department of Anesthesiology, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA; Harvard Medical School, Boston, MA, USA.
| | - Edward A Bittner
- Department of Anesthesiology, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA; Shriners Hospitals for Children, Boston, MA, USA; Harvard Medical School, Boston, MA, USA
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Madjroh N, Mellou E, Davies PA, Söderhielm PC, Jensen AA. Discovery and functional characterization of N-(thiazol-2-yl)-benzamide analogs as the first class of selective antagonists of the Zinc-Activated Channel (ZAC). Biochem Pharmacol 2021; 193:114782. [PMID: 34560054 PMCID: PMC9979163 DOI: 10.1016/j.bcp.2021.114782] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 09/08/2021] [Accepted: 09/13/2021] [Indexed: 10/20/2022]
Abstract
The Zinc-Activated Channel (ZAC) is an atypical member of the Cys-loop receptor (CLR) superfamily of pentameric ligand-gated ion channels, with its very different endogenous agonists and signalling properties. In this study, a compound library screening at ZAC resulted in the identification of 2-(5-bromo-2-chlorobenzamido)-4-methylthiazole-5-methyl ester (1) as a novel ZAC antagonist. The structural determinants for ZAC activity in 1 were investigated by functional characterization of 61 analogs at ZAC expressed in Xenopus oocytes by two-electrode voltage clamp electrophysiology, and couple of analogs exerting more potent ZAC inhibition than 1 were identified (IC50 values: 1-3 μM). 1 and N-(4-(tert-butyl)thiazol-2-yl)-3-fluorobenzamide (5a, TTFB) were next applied in studies of the functional properties and the mode of action of this novel class of ZAC antagonists. TTFB was a roughly equipotent antagonist of Zn+- and H+-evoked ZAC signaling and of spontaneous ZAC activity, and the slow on-set of its channel block suggested that its ZAC inhibition is state-dependent. TTFB was found to be a selective ZAC antagonist, exhibiting no significant agonist, antagonist or modulatory activity at 5-HT3A, α3β4 nicotinic acetylcholine, α1β2γ2S GABAA or α1 glycine receptors at 30 μM. 1 displayed largely non-competitive antagonism of Zn2+-induced ZAC signalling, and TTFB was demonstrated to target the transmembrane and/or intracellular domains of the receptor, which collectively suggests that the N-(thiazol-2-yl)-benzamide analog acts a negative allosteric modulator of ZAC. We propose that this first class of selective ZAC antagonists could constitute useful pharmacological tools in future explorations of the presently poorly elucidated physiological functions governed by this CLR.
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Affiliation(s)
- Nawid Madjroh
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen Ø, Denmark
| | - Eleni Mellou
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen Ø, Denmark
| | - Paul A. Davies
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, USA
| | - Pella C. Söderhielm
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen Ø, Denmark
| | - Anders A. Jensen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen Ø, Denmark,Corresponding author. (A.A. Jensen)
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Hoshino H, Furutani E. On the relationship between inhibition and receptor occupancy by nondepolarizing neuromuscular blocking drugs. Theor Biol Med Model 2021; 18:15. [PMID: 34419079 PMCID: PMC8379761 DOI: 10.1186/s12976-021-00147-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 07/27/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Nondepolarizing neuromuscular blocking drugs (NDNBs) are clinically used to produce muscle relaxation during general anesthesia. To better understand clinical properties of NDNBs, comparative in vitro pharmacologic studies have been performed. In these studies, a receptor binding model, which relies on the assumption that the inhibition, i.e., the effect of an NDNB, is proportional to the receptor occupancy by the drug, has been effectively used to describe obtained experimental data. However, it has not been studied in literature under which conditions the above assumption can be justified nor the assumption still holds in vivo. The purpose of this study is to explore the in vivo relationship between the inhibition and the receptor occupancy by an NDNB and to draw implications on how in vitro experimental results can be used to discuss the in vivo properties of NDNBs. METHODS An ordinary differential equation model is employed to simulate physiologic processes of the activation of receptors by acetylcholine (ACh) as well as inhibition by an NDNB. With this model, the degree of inhibition is quantified by the fractional amount of receptors that are not activated by ACh due to the presence of an NDNB. The results are visualized by plotting the fractional amounts of the activated receptors as a function of the receptor occupancy. RESULTS Numerical investigations reflecting in vivo conditions show that the degree of inhibition is not proportional to the receptor occupancy, i.e., there is a nonlinear relationship between the inhibition and the receptor occupancy. However, under a setting of high concentration of ACh reflecting a typical situation of in vitro experiments, the relationship between the inhibition and the receptor occupancy becomes linear, suggesting the validity of the receptor binding model. Also, it is found that the extent of nonlinearity depends on the selectivity of NDNBs for the two binding sites of the receptors. CONCLUSIONS While the receptor binding model may be effective for estimating affinity of an NDNB through in vitro experiments, these models do not directly describe in vivo properties of NDNBs, because the nonlinearity between the inhibition and the receptor occupancy causes the modulation of the resultant concentration-effect relationships of NDNBs.
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Affiliation(s)
- Hikaru Hoshino
- Department of Electrical Materials and Engineering, University of Hyogo, Hyogo, Japan.
| | - Eiko Furutani
- Department of Electrical Materials and Engineering, University of Hyogo, Hyogo, Japan.,Department of Anesthesiology, Kagawa University, Kagawa, Japan
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Goswami LN, Olds TJ, Monk TG, Johnson QL, Dilger JP, Shanawaz MA, Jalisatgi SS, Hawthorne MF, Kracke GR. Isomeric Carborane Neuromuscular Blocking Agents. ChemMedChem 2019; 14:1108-1114. [DOI: 10.1002/cmdc.201800817] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Revised: 03/06/2019] [Indexed: 01/13/2023]
Affiliation(s)
- Lalit N. Goswami
- International Institute of Nano and Molecular MedicineUniversity of Missouri Columbia MO 65212 USA
| | - Tyson J. Olds
- Department of Anesthesiology and Perioperative MedicineUniversity of Missouri School of Medicine, Dalton Cardiovascular Research Center (GRK) Columbia MO 65212 USA
| | - Terri G. Monk
- Department of Anesthesiology and Perioperative MedicineUniversity of Missouri School of Medicine, Dalton Cardiovascular Research Center (GRK) Columbia MO 65212 USA
| | - Quinn L. Johnson
- Department of Anesthesiology and Perioperative MedicineUniversity of Missouri School of Medicine, Dalton Cardiovascular Research Center (GRK) Columbia MO 65212 USA
| | - James P. Dilger
- Stony Brook UniversityDepartment of Anesthesiology Stony Brook NY 11794 USA
| | | | - Satish S. Jalisatgi
- International Institute of Nano and Molecular MedicineUniversity of Missouri Columbia MO 65212 USA
| | - M. Frederick Hawthorne
- International Institute of Nano and Molecular MedicineUniversity of Missouri Columbia MO 65212 USA
| | - George R. Kracke
- Department of Anesthesiology and Perioperative MedicineUniversity of Missouri School of Medicine, Dalton Cardiovascular Research Center (GRK) Columbia MO 65212 USA
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Park WY, Choi JC, Yun HJ, Jeon YG, Park G, Choi JB. Optimal dose of combined rocuronium and cisatracurium during minor surgery: A randomized trial. Medicine (Baltimore) 2018; 97:e9779. [PMID: 29517695 PMCID: PMC5882426 DOI: 10.1097/md.0000000000009779] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 12/14/2017] [Accepted: 01/11/2018] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Combined rocuronium and cisatracurium have synergistic effects. We investigated whether reduced doses are effective during coadministration, by monitoring neuromuscular relaxation during surgery. METHODS This randomized, controlled clinical trial was registered at http://clinicaltrials.gov (registration number NCT02495038). The participants were 81 patients scheduled for elective mastoidectomy and tympanoplasty. Participants were assigned to groups, including the intubating dose group (Group I, n = 27; combined ED95 rocuronium and ED95 cisatracurium), the small reduction group (Group S, n = 27; dose reduced by 10% of each ED95), or the large reduction group (Group L, n = 27; dose reduced by 20% of each ED95). Drugs were administered to patients and a timer was started using TOF-Watch monitoring. TOF (train-of-four) was monitored at the ulnar nerve, at a setting of 2 Hz/12 s. We recorded the time to TOF ratio = 0 (onset), time to first TOF ratio > 25% (duration 25%), and TOF 25-75% (recovery index) under total intravenous anesthesia. One-way analysis of variance was used for statistical analyses (α = 0.05, β = 0.2). RESULTS There were no significant demographic differences between groups. Group L had a longer duration to onset (mean ± standard deviation, 399.3 ± 147.8 seconds) and shorter duration 25% (39.4 ± 6.8 minutes) compared to Group I (212.8 ± 56.0 s and 51.3 ± 8.47 minutes, respectively) and Group S (230.7 ± 60.6 s and 47.9 ± 10.7 minutes, respectively). There were no other significant differences between groups. CONCLUSION Our findings contribute to determining clinically effective combinations of rocuronium and cisatracurium, as well as to predicting the pharmacokinetic characteristics of the synergistic effects. We suggest that reducing doses of both drugs by approximately 10% of their respective ED95 values is sufficient to maintain neuromuscular relaxation during minor surgery.
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Affiliation(s)
- Woo Young Park
- Department of Anesthesiology and Pain Medicine, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
- Department of Anesthesia, Sheikh Khalifa Specialty Hospital, Ras Al Khaimah, United Arab Emirates
| | - Jae Chan Choi
- Department of Anesthesiology and Pain Medicine, Intensive Care Medicine, Brain Research Group, Yonsei University Wonju College of Medicine, Wonju
| | - Hey Jeong Yun
- Department of Anesthesia, Sheikh Khalifa Specialty Hospital, Ras Al Khaimah, United Arab Emirates
| | | | - Gisoon Park
- Department of Anesthesiology and Pain Medicine, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
| | - Jong Bum Choi
- Department of Anesthesiology and Pain Medicine, Ajou University, College of Medicine, Suwon, Republic of Korea
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Yu B, Ouyang B, Ge S, Luo Y, Li J, Ni D, Hu S, Xu H, Liu J, Min S, Li L, Ma Z, Xie K, Miao C, Wu X. Incidence of postoperative residual neuromuscular blockade after general anesthesia: a prospective, multicenter, anesthetist-blind, observational study. Curr Med Res Opin 2016; 32:1-9. [PMID: 26452561 DOI: 10.1185/03007995.2015.1103213] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
OBJECTIVE Evidences demonstrate that postoperative residual neuromuscular blockade (rNMB) is a primary and frequent anesthetic risk factor for postoperative complications. This study was designed to mitigate the paucity of data regarding the occurrence and degree of rNMB in a real-life setting. METHODS This prospective, multicenter, anesthetist-blind, observational study enrolled 1571 Chinese adults undergoing elective open or laparoscopic abdominal surgery lasting ≤4 hours from 32 hospitals across China. The patients received anesthesia in accordance with routine practice at the study site. Neuromuscular blockade (NMB) was monitored using acceleromyography, with rNMB defined as a train-of-four (TOF) ratio <0.9. RESULTS The patients' mean age was 46 years and 71% were female. The procedures included laparoscopic (67%), open abdominal (31%), and laparoscopic to open abdominal (2%). NMB was reversed with neostigmine in 78% of patients. The overall incidence of rNMB at extubation was 57.8%, and the proportions of participant with TOF ratios <0.6, 0.6-0.7, 0.7-0.8, 0.8-0.9 were 22.9%, 6.9%, 11.1% and 16.9%, respectively, immediately prior to endotracheal extubation. Age <45 years (OR = 0.630, 95% CI = 0.496-0.801, p = 0.002), use of one neuromuscular blocking agent (NMBA) (OR = 0.387, 95% CI = 0.243-0.618, p < 0.0001), time from neostigmine administration to endotracheal extubation ≥10 min (OR = 0.513, 95% CI = 0.400-0.658, p < 0.0001) and time from last NMBA administration to endotracheal extubation ≥60 min (OR = 0.902, 95% CI = 0.801-0.989, p = 0411) were correlated with non-rNMB at the time of extubation. CONCLUSIONS This observational study demonstrated that the overall incidence of rNMB at the time of endotracheal extubation was high in Chinese patients undergoing abdominal procedures, which necessitates appropriate management in current real-life practice. CLINICAL TRIAL REGISTRY NUMBER NCT01871064.
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Affiliation(s)
- Buwei Yu
- a a Department of Anesthesiology , Rui Jin Hospital, Shanghai Jiao Tong University School of Medicine , Shanghai , China
| | - Baoyi Ouyang
- b b The First Affiliated hospital of Guangzhou Medical University , Guangzhou , China
| | - Shengjin Ge
- c c Zhongshan Hospital of Fudan University , Shanghai , China
| | - Yan Luo
- a a Department of Anesthesiology , Rui Jin Hospital, Shanghai Jiao Tong University School of Medicine , Shanghai , China
| | - Jun Li
- d d The Second Affiliated Hospital of Wenzhou Medical College , Wenzhou , China
| | - Dongmei Ni
- e e Peking University First Hospital , Beijing , China
| | - Shuangfei Hu
- f f Zhejiang Provincial People's Hospital , Hangzhou , China
| | - Hui Xu
- g g Tongji Hospital, Tongji Medical College of Huazhong University of Science & Technology , Wuhan , China
| | - Jin Liu
- h h West China Hospital, West China School of Medicine, Sichuan University , Chengdu , China
| | - Su Min
- i i The First Affiliated Hospital of Chongqing Medical University , Chongqing , China
| | - Longyun Li
- j j China-Japan Union Hospital, Jilin University , Changchun , China
| | - Zhengliang Ma
- k k Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School , Nanjing , China
| | - Kangjie Xie
- l l Zhejiang Cancer Hospital , Hangzhou , China
| | - Changhong Miao
- m m Fudan University Shanghai Cancer Center , Shanghai , China
| | - Xinmin Wu
- e e Peking University First Hospital , Beijing , China
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Woehrling EK, Parri HR, Tse EHY, Hill EJ, Maidment ID, Fox GC, Coleman MD. A predictive in vitro model of the impact of drugs with anticholinergic properties on human neuronal and astrocytic systems. PLoS One 2015; 10:e0118786. [PMID: 25738989 PMCID: PMC4349811 DOI: 10.1371/journal.pone.0118786] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Accepted: 01/22/2015] [Indexed: 11/19/2022] Open
Abstract
The link between off-target anticholinergic effects of medications and acute cognitive impairment in older adults requires urgent investigation. We aimed to determine whether a relevant in vitro model may aid the identification of anticholinergic responses to drugs and the prediction of anticholinergic risk during polypharmacy. In this preliminary study we employed a co-culture of human-derived neurons and astrocytes (NT2.N/A) derived from the NT2 cell line. NT2.N/A cells possess much of the functionality of mature neurons and astrocytes, key cholinergic phenotypic markers and muscarinic acetylcholine receptors (mAChRs). The cholinergic response of NT2 astrocytes to the mAChR agonist oxotremorine was examined using the fluorescent dye fluo-4 to quantitate increases in intracellular calcium [Ca2+]i. Inhibition of this response by drugs classified as severe (dicycloverine, amitriptyline), moderate (cyclobenzaprine) and possible (cimetidine) on the Anticholinergic Cognitive Burden (ACB) scale, was examined after exposure to individual and pairs of compounds. Individually, dicycloverine had the most significant effect regarding inhibition of the astrocytic cholinergic response to oxotremorine, followed by amitriptyline then cyclobenzaprine and cimetidine, in agreement with the ACB scale. In combination, dicycloverine with cyclobenzaprine had the most significant effect, followed by dicycloverine with amitriptyline. The order of potency of the drugs in combination frequently disagreed with predicted ACB scores derived from summation of the individual drug scores, suggesting current scales may underestimate the effect of polypharmacy. Overall, this NT2.N/A model may be appropriate for further investigation of adverse anticholinergic effects of multiple medications, in order to inform clinical choices of suitable drug use in the elderly.
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Affiliation(s)
- Elizabeth K. Woehrling
- School of Life and Health Sciences, Aston University, Birmingham, B4 7ET, United Kingdom
| | - H. Rheinallt Parri
- School of Life and Health Sciences, Aston University, Birmingham, B4 7ET, United Kingdom
| | - Erin H. Y. Tse
- School of Life and Health Sciences, Aston University, Birmingham, B4 7ET, United Kingdom
| | - Eric J. Hill
- Aston Research Centre into Healthy Ageing (ARCHA), Aston University, Birmingham, B4 7ET, United Kingdom
| | - Ian D. Maidment
- Aston Research Centre into Healthy Ageing (ARCHA), Aston University, Birmingham, B4 7ET, United Kingdom
| | - G. Christopher Fox
- Norwich Medical School, Faculty of Medicine and Health Sciences, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, United Kingdom
| | - Michael D. Coleman
- School of Life and Health Sciences, Aston University, Birmingham, B4 7ET, United Kingdom
- * E-mail:
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Jung KT, Kim JW, Kim TK, An TH. A comparison of the clinical duration and recovery characteristics of cisatracurium after priming using rocuronium or cisatracurium: preliminary study. Korean J Anesthesiol 2014; 66:18-22. [PMID: 24567808 PMCID: PMC3926995 DOI: 10.4097/kjae.2014.66.1.18] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Revised: 05/30/2013] [Accepted: 06/26/2013] [Indexed: 11/28/2022] Open
Abstract
Background The priming technique can speed up the onset of cisatracurium during intubation. However, there have been no reports on the effect of the priming technique on duration or recovery profile of cisatracurium. Therefore, we attempted to determine whether or not a priming technique with rocuronium or cisatracurium can affect clinical duration or recovery profiles of cisatracurium. Methods A total of 36 patients, ASA I and II, who were scheduled to undergo elective surgery, were enrolled. The patients were randomized into three groups and administered different drugs for the priming technique. Patients in group 1 received normal saline (control group). Patients in group 2 received rocuronium (0.06 mg/kg), and those in group 3 received cisatracurium (0.01 mg/kg) as a priming agent. Three minutes after injection of drugs, intubation doses of cisatracurium were administered (Group 1, 0.15 mg/kg; Groups 2 and 3, 0.14 mg/kg). Anesthesia was induced and maintained with propofol and remifentanil. Onset time, clinical duration, recovery index, recovery time, and total recovery time were measured by train of four monitoring. Results Onset time in the group 2 was significantly shorter than that of group 1 or 3 (P < 0.05). However, no significant differences in clinical duration, recovery index, recovery time, and total recovery time were observed among the three groups. Conclusions Priming with rocuronium for 3 minutes resulted in significantly accelerated onset of cisatracurium. However, it did not affect the clinical duration and recovery profiles of cisatracurium.
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Affiliation(s)
- Ki Tae Jung
- Department of Anesthesiology and Pain Medicine, School of Medicine, Chosun University, Gwangju, Korea
| | - Jae Wook Kim
- Department of Anesthesiology and Pain Medicine, School of Medicine, Chosun University, Gwangju, Korea
| | - Tong Kyu Kim
- Department of Anesthesiology and Pain Medicine, School of Medicine, Chosun University, Gwangju, Korea
| | - Tae Hun An
- Department of Anesthesiology and Pain Medicine, School of Medicine, Chosun University, Gwangju, Korea
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Abstract
BACKGROUND The onset time for paralysis varies 3-fold among nondepolarizing muscle relaxants. Possible explanations include: (a) pharmacokinetic differences among drugs and (b) buffering of drug molecules by acetylcholine receptors as they diffuse into the neuromuscular junction. Although some pharmacokinetic models consider buffered diffusion, these models do not account for either the high density of receptors or synapse geometry. Here, I used computer simulations to calculate the kinetics of buffered diffusion. The goal was to determine the conditions under which buffered diffusion could account for differences in onset time among nondepolarizing muscle relaxants. METHODS Monte Carlo simulation was used along with a realistic 3-dimensional model of the rat neuromuscular junction. Simulations determined the time dependence of the number of drug-bound receptors. A 1000-fold range of drug potency was examined. In some simulations, the drug concentration outside the junction was changed instantaneously. In other simulations, the concentration changed according to predictions of pharmacokinetic models assuming time-dependent changes in plasma drug concentration. The rate constant for equilibration of drug between plasma and muscle, keo, was varied between 0.15 and 0.6 min(-1). Twitch amplitude was calculated from receptor occupancy assuming a high safety margin for neuromuscular transmission. Some simulations used a synaptic model with an increased nerve-muscle contact width. RESULTS Simulations with instantaneous changes in drug concentration at the synapse, indicated that the time to 50% twitch depression (onset time) was 0.1 to 30 seconds and was proportional to drug potency. This corresponds to iontophoretic application of drug to isolated neuromuscular junctions, but is too fast to explain onset times in humans. When pharmacokinetic models were used to calculate the drug concentration outside the synapse, buffered diffusion increased onset times of potent drugs (drugs for which the effective concentration at 50% twitch height is <600 nM). Simulations using keo = 0.6 min(-1) and a model with a 2- to 3-fold wider nerve-muscle contact width indicated that buffered diffusion could account for the differences in clinical onset times among the nondepolarizing muscle relaxants. CONCLUSION Monte Carlo simulation provides a biophysically appropriate way to incorporate buffered diffusion into pharmacokinetic modeling. The simulations indicated that buffered diffusion could account for differences in onset time among drugs. However, a better understanding of the geometry of the human neuromuscular junction is needed before the magnitude of the effect of buffered diffusion can be quantified.
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16-Morpholino quaternary ammonium steroidal derivatives as neuromuscular blocking agents: Synthesis, biological evaluation and in silico probe of ligand–receptor interaction. Eur J Med Chem 2012; 56:332-47. [DOI: 10.1016/j.ejmech.2012.07.048] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2012] [Revised: 07/23/2012] [Accepted: 07/31/2012] [Indexed: 11/19/2022]
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Goldschen-Ohm MP, Wagner DA, Jones MV. Three arginines in the GABAA receptor binding pocket have distinct roles in the formation and stability of agonist- versus antagonist-bound complexes. Mol Pharmacol 2011; 80:647-56. [PMID: 21764985 DOI: 10.1124/mol.111.072033] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Binding of the agonist GABA to the GABA(A) receptor causes channel gating, whereas competitive antagonists that bind at the same site do not. The details of ligand binding are not well understood, including which residues interact directly with ligands, maintain the structure of the binding pocket, or transduce the action of binding into opening of the ion channel gate. Recent work suggests that the amine group of the GABA molecule may form a cation-π bond with residues in a highly conserved "aromatic box" within the binding pocket. Although interactions with the carboxyl group of GABA remain unknown, three positively charged arginines (α(1)Arg67, α(1)Arg132, and β(2)Arg207) just outside of the aromatic box are likely candidates. To explore their roles in ligand binding, we individually mutated these arginines to alanine and measured the effects on microscopic ligand binding/unbinding rates and channel gating. The mutations α(1)R67A or β(2)R207A slowed agonist binding and sped unbinding with little effect on gating, demonstrating that these arginines are critical for both formation and stability of the agonist-bound complex. In addition, α(1)R67A sped binding of the antagonist 2-(3-carboxypropyl)-3-amino-6-(4 methoxyphenyl)pyridazinium bromide (SR-95531), indicating that this arginine poses a barrier to formation of the antagonist-bound complex. In contrast, β(2)R207A and α(1)R132A sped antagonist unbinding, indicating that these arginines stabilize the antagonist-bound state. α(1)R132A also conferred a new long-lived open state, indicating that this arginine influences the channel gate. Thus, each of these arginines plays a unique role in determining interactions with agonists versus antagonists and with the channel gate.
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Dilger JP. Monte Carlo simulation of buffered diffusion into and out of a model synapse. Biophys J 2010; 98:959-67. [PMID: 20303853 DOI: 10.1016/j.bpj.2009.11.034] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2009] [Revised: 11/10/2009] [Accepted: 11/18/2009] [Indexed: 10/19/2022] Open
Abstract
Buffered diffusion occurs when ligands enter or leave a restricted space, such as a chemical synapse, containing a high density of binding sites. This study used Monte Carlo simulations to determine the time and spatial dependences of buffered diffusion without a priori assumptions about kinetics. The synapse was modeled as a box with receptors on one inner face. The exterior was clamped to some ligand concentration and ligands diffused through two sides. Onset and recovery simulations were carried out and the effects of receptor density, ligand properties and synapse geometry were investigated. This study determined equilibration times for binding and the spatial gradient of unliganded receptors. Onset was characterized by a high spatial gradient; equilibration was limited by the time needed for sufficient ligands to enter the synapse. Recovery showed a low spatial gradient with receptor equilibration limited by ligand rebinding. Decreasing ligand association rate or increasing ligand diffusion coefficient reduced the role of buffered diffusion and decreased the spatial gradient. Simulations with irreversible ligands showed larger, persistent spatial gradients. These simulations identify characteristics that can be used to test whether a synaptic process is governed by buffered diffusion. They also indicate that fundamental differences in synapse function may occur with irreversible ligands.
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Affiliation(s)
- James P Dilger
- Department of Anesthesiology, Stony Brook University, Stony Brook, New York, USA.
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Lee JH, Lee SI, Lee SC, Cho WJ. Analysis of the rocuronium-vecuronium interaction on tetanic fade based on a generalized response surface model with varying relative potencies. Korean J Anesthesiol 2009; 56:559-566. [PMID: 30625788 DOI: 10.4097/kjae.2009.56.5.559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Some studies have shown that rocuronium and vecuronium have additive, or synergistic effects on muscle relaxation based on the Loewe additivity. Therefore, we performed a fit of tetanic fade data to a generalized response surface model with varying relative potencies proposed by Kong and Lee (KLGRS) to evaluate the usefulness of KLGRS for capturing the interspersed drug interactions and to characterize the interaction between the two drugs. METHODS Left phrenic nerve-hemidiaphragms (Male Sprague-Dawley rats, 150-250 g) were mounted in Krebs solution. Supramaximal electrical stimulation (0.2 ms, rectangular) of 50 Hz for 1.9 s to the phrenic nerve evoked tetanic contractions that were measured with a force transducer. Each preparation was exposed to one of 4 vecuronium concentrations (0.0, 1.5, 2.5, and 3.0 microM), or one of 4 rocuronium concentrations (0.0, 3.0, 4.5, and 5.5 microM). Subsequently the adequate amount of rocuronium was added to a vecuronium bath and that of vecuronium was added to a rocuronium until an 80-90% increase in tetanic fade was achieved. We then fitted the modified KLGRS models to the above data, after which we selected the best model, based on 5 methods for determining goodness of fit. Using this method, we obtained the response surface, as well as contour plots for the response surface (i.e. isoboles), the polynomial function and the interaction index. RESULTS The model with the constant relative potency ratio and 8 parameters was found to best describe the results, and this model reflected well the characteristics of the raw data. In addition, the two drugs showed a synergistic interaction in almost every area and an antagonistic one in a very narrow area. CONCLUSIONS KLGRS was found to be a useful method of analyzing data describing interspersed drug interactions. The interaction between rocuronium and vecuronium was found to be synergistic.
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Affiliation(s)
- Jong Hwan Lee
- Department of Anesthesiology and Pain Medicine, Dong-A University Medicine College, Busan, Korea.
| | - Soo Il Lee
- Department of Anesthesiology and Pain Medicine, Dong-A University Medicine College, Busan, Korea.
| | - Seung Cheol Lee
- Department of Anesthesiology and Pain Medicine, Dong-A University Medicine College, Busan, Korea.
| | - Won Joon Cho
- Department of Anesthesiology and Pain Medicine, Dong-A University Medicine College, Busan, Korea.
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Liu M, Dilger JP. Site selectivity of competitive antagonists for the mouse adult muscle nicotinic acetylcholine receptor. Mol Pharmacol 2008; 75:166-73. [PMID: 18842832 DOI: 10.1124/mol.108.051060] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The muscle-type nicotinic acetylcholine receptor has two nonidentical binding sites for ligands. The selectivity of acetylcholine and the competitive antagonists (+)-tubocurarine and metocurine for adult mouse receptors is known. Here, we examine the site selectivity for four other competitive antagonists: cisatracurium, pancuronium, vecuronium, and rocuronium. We rapidly applied acetylcholine to outside-out patches from transfected BOSC23 cells and measured macroscopic currents. We have reported the IC(50) of the antagonists individually in prior publications. Here, we determined inhibition by pairs of competitive antagonists. At least one antagonist was present at a concentration producing > or =67% receptor inhibition. Metocurine shifted the apparent IC(50) of (+)-tubocurarine in quantitative agreement with complete competitive antagonism. The same was observed for pancuronium competing with vecuronium. However, pancuronium and vecuronium each shifted the apparent IC(50) of (+)-tubocurarine less than expected for complete competition but more than expected for independent binding. The situation was similar for cisatracurium and (+)-tubocurarine or metocurine. Cisatracurium did not shift the apparent IC(50) of pancuronium or vecuronium, indicating independent binding of these two pairs. The data were fit to a two-site, two-antagonist model to determine the antagonist binding constants for each site, L(alphaepsilon) and L(alphadelta). We found L(alphaepsilon)/L(alphadelta) = 0.22 (range, 0.14-0.34), 20 (9-29), 21 (4-36), and 1.5 (0.3-2.9) for cisatracurium, pancuronium, vecuronium, and rocuronium, respectively. The wide range of L(alphaepsilon)/L(alphadelta) for some antagonists may reflect experimental uncertainties in the low affinity site, relatively poor selectivity (rocuronium), or possibly that the binding of an antagonist at one site affects the affinity of the second site.
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Affiliation(s)
- Man Liu
- Department of Anesthesiology, Stony Brook University, Stony Brook, NY 11790-8480, USA
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15
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Dilger JP, Vidal AM, Liu M, Mettewie C, Suzuki T, Pham A, Demazumder D. Roles of amino acids and subunits in determining the inhibition of nicotinic acetylcholine receptors by competitive antagonists. Anesthesiology 2007; 106:1186-95. [PMID: 17525594 PMCID: PMC2367005 DOI: 10.1097/01.anes.0000267602.94516.7f] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Binding sites for agonists and competitive antagonists (nondepolarizing neuromuscular blocking agents) are located at the alpha-delta and alpha-epsilon subunit interfaces of adult nicotinic acetylcholine receptors. Most information about the amino acids that participate in antagonist binding comes from binding studies with (+)-tubocurarine and metocurine. These bind selectively to the alpha-epsilon interface but are differentially sensitive to mutations. To test the generality of this observation, the authors measured current inhibition by five competitive antagonists on wild-type and mutant acetylcholine receptors. METHODS HEK293 cells were transfected with wild-type or mutant (alphaY198F, epsilonD59A, epsilonD59N, epsilonD173A, epsilonD173N, deltaD180K) mouse muscle acetylcholine receptor complementary DNA. Outside-out patches were excised and perfused with acetylcholine in the absence and presence of antagonist. Concentration-response curves were constructed to determine antagonist IC50. An antagonist-removal protocol was used to determine dissociation and association rates. RESULTS Effects of mutations were antagonist specific. alphaY198F decreased the IC50 of (+)-tubocurarine 10-fold, increased the IC50 of vecuronium 5-fold, and had smaller effects on other antagonists. (+)-Tubocurarine was the most sensitive antagonist to epsilonD173 mutations. epsilonD59 mutations had large effects on metocurine and cisatracurium. deltaD180K decreased inhibition by pancuronium, vecuronium, and cisatracurium. Inhibition by these antagonists was increased for receptors containing two delta subunits but no epsilon subunit. Differences in IC50 arose from differences in both dissociation and association rates. CONCLUSION Competitive antagonists exhibited different patterns of sensitivity to mutations. Except for pancuronium, the antagonists were sensitive to mutations at the alpha-epsilon interface. Pancuronium, vecuronium, and cisatracurium were selective for the alpha-delta interface. This suggests the possibility of synergistic inhibition by pairs of antagonists.
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Affiliation(s)
- James P Dilger
- Department of Anesthesiology, Stony Brook University, NY 11794-8480, USA, and Department of Anesthesiology, Surugadai Nihon University Hospital, Kanda, Tokyo, Japan.
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