1
|
Hao X, Ou M, Li Y, Zhou C. Volatile anesthetics maintain tidal volume and minute ventilation to a greater degree than propofol under spontaneous respiration. BMC Anesthesiol 2021; 21:238. [PMID: 34615483 PMCID: PMC8493718 DOI: 10.1186/s12871-021-01438-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Accepted: 08/28/2021] [Indexed: 02/08/2023] Open
Abstract
Background Although general anesthetics depress spontaneous respiration, the comprehensive effect of general anesthetics on respiratory function remains unclear. We aimed to investigate the effects of general anesthetics on spontaneous respiration in non-intubated mice with different types and doses of general anesthetic. Methods Adult C57BL/6 J mice were administered intravenous anesthetics, including propofol and etomidate, and inhalational anesthetics, including sevoflurane and isoflurane in vivo at doses of 0.5-, 1.0-, and 2.0-times the minimum alveolar concentration (MAC)/median effective dose (ED50) to induce loss of the righting reflex (LORR). Whole-body plethysmography (WBP) was applied to measure parameters of respiration under unrestricted conditions without endotracheal intubation. The alteration in respiratory sensitivity to carbon dioxide (CO2) under general anesthesia was also determined. The following respiratory parameters were continuously recorded during anesthesia or CO2 exposure: respiratory frequency (FR), tidal volume (TV), minute ventilation (MV), expiratory time (TE), inspiratory time (TI), and inspiratory–expiratory time ratio (I/E), and peak inspiratory flow. Results Sub-anesthetic concentrations (0.5 MAC) of sevoflurane or isoflurane increased FR, TV, and MV. With isoflurane and sevoflurane exposure, the CO2-evoked increases in FR, TV, and MV were decreased. Compared with inhalational anesthetics, propofol and etomidate induced respiratory suppression, affecting FR, TV, and MV. In 100% oxygen (O2), FR in the group that received propofol 1.0-times the ED50 was 69.63 ± 33.44 breaths/min compared with 155.68 ± 64.42 breaths/min in the etomidate-treated group. In the same groups, FR was 88.72 ± 34.51 breaths/min and 225.10 ± 59.82 breaths/min, respectively, in 3% CO2 and 144.17 ± 63.25 breaths/min and 197.70 ± 41.93 breaths/min, respectively, in 5% CO2. A higher CO2 sensitivity was found in etomidate-treated mice compared with propofol-treated mice. In addition, propofol induced a greater decrease in FR, MV, and I/E ratio compared with etomidate, sevoflurane, and isoflurane at equivalent doses (all P < 0.05). Conclusions General anesthetics differentially modulate spontaneous breathing in vivo. Volatile anesthetics increase FR, TV, and MV at sub-anesthetic concentrations, while they decrease FR at higher concentrations. Propofol consistently depressed respiratory parameters to a greater degree than etomidate.
Collapse
Affiliation(s)
- Xuechao Hao
- Departments of Anesthesiology, West China Hospital of Sichuan University, Chengdu, 610041, China.,Laboratory of Anesthesia & Critical Care Medicine, Translational Neuroscience Center, The Research Units of West China-Chinese Academy of Medical Sciences, West China Hospital of Sichuan University, Chengdu, 610041, China
| | - Mengchan Ou
- Departments of Anesthesiology, West China Hospital of Sichuan University, Chengdu, 610041, China.,Laboratory of Anesthesia & Critical Care Medicine, Translational Neuroscience Center, The Research Units of West China-Chinese Academy of Medical Sciences, West China Hospital of Sichuan University, Chengdu, 610041, China
| | - Yu Li
- Departments of Anesthesiology, West China Hospital of Sichuan University, Chengdu, 610041, China.
| | - Cheng Zhou
- Departments of Anesthesiology, West China Hospital of Sichuan University, Chengdu, 610041, China. .,Laboratory of Anesthesia & Critical Care Medicine, Translational Neuroscience Center, The Research Units of West China-Chinese Academy of Medical Sciences, West China Hospital of Sichuan University, Chengdu, 610041, China.
| |
Collapse
|
2
|
Mashour GA, Palanca BJA, Basner M, Li D, Wang W, Blain-Moraes S, Lin N, Maier K, Muench M, Tarnal V, Vanini G, Ochroch EA, Hogg R, Schwartz M, Maybrier H, Hardie R, Janke E, Golmirzaie G, Picton P, McKinstry-Wu AR, Avidan MS, Kelz MB. Recovery of consciousness and cognition after general anesthesia in humans. eLife 2021; 10:59525. [PMID: 33970101 PMCID: PMC8163502 DOI: 10.7554/elife.59525] [Citation(s) in RCA: 52] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 05/06/2021] [Indexed: 12/13/2022] Open
Abstract
Understanding how the brain recovers from unconsciousness can inform neurobiological theories of consciousness and guide clinical investigation. To address this question, we conducted a multicenter study of 60 healthy humans, half of whom received general anesthesia for 3 hr and half of whom served as awake controls. We administered a battery of neurocognitive tests and recorded electroencephalography to assess cortical dynamics. We hypothesized that recovery of consciousness and cognition is an extended process, with differential recovery of cognitive functions that would commence with return of responsiveness and end with return of executive function, mediated by prefrontal cortex. We found that, just prior to the recovery of consciousness, frontal-parietal dynamics returned to baseline. Consistent with our hypothesis, cognitive reconstitution after anesthesia evolved over time. Contrary to our hypothesis, executive function returned first. Early engagement of prefrontal cortex in recovery of consciousness and cognition is consistent with global neuronal workspace theory.
Collapse
Affiliation(s)
- George A Mashour
- Center for Consciousness Science, Department of Anesthesiology, University of Michigan Medical SchoolAnn ArborUnited States
| | - Ben JA Palanca
- Department of Anesthesiology, Washington University School of MedicineSt. LouisUnited States
| | - Mathias Basner
- Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of PennsylvaniaPhiladelphiaUnited States
| | - Duan Li
- Center for Consciousness Science, Department of Anesthesiology, University of Michigan Medical SchoolAnn ArborUnited States
| | - Wei Wang
- Department of Mathematics and Statistics, Washington UniversitySt. LouisUnited States
| | - Stefanie Blain-Moraes
- Center for Consciousness Science, Department of Anesthesiology, University of Michigan Medical SchoolAnn ArborUnited States
| | - Nan Lin
- Department of Mathematics and Statistics, Washington UniversitySt. LouisUnited States
| | - Kaitlyn Maier
- Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of PennsylvaniaPhiladelphiaUnited States
| | - Maxwell Muench
- Department of Anesthesiology, Washington University School of MedicineSt. LouisUnited States
| | - Vijay Tarnal
- Center for Consciousness Science, Department of Anesthesiology, University of Michigan Medical SchoolAnn ArborUnited States
| | - Giancarlo Vanini
- Center for Consciousness Science, Department of Anesthesiology, University of Michigan Medical SchoolAnn ArborUnited States
| | - E Andrew Ochroch
- Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of PennsylvaniaPhiladelphiaUnited States
| | - Rosemary Hogg
- Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of PennsylvaniaPhiladelphiaUnited States
| | - Marlon Schwartz
- Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of PennsylvaniaPhiladelphiaUnited States
| | - Hannah Maybrier
- Department of Anesthesiology, Washington University School of MedicineSt. LouisUnited States
| | - Randall Hardie
- Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of PennsylvaniaPhiladelphiaUnited States
| | - Ellen Janke
- Center for Consciousness Science, Department of Anesthesiology, University of Michigan Medical SchoolAnn ArborUnited States
| | - Goodarz Golmirzaie
- Center for Consciousness Science, Department of Anesthesiology, University of Michigan Medical SchoolAnn ArborUnited States
| | - Paul Picton
- Center for Consciousness Science, Department of Anesthesiology, University of Michigan Medical SchoolAnn ArborUnited States
| | - Andrew R McKinstry-Wu
- Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of PennsylvaniaPhiladelphiaUnited States
| | - Michael S Avidan
- Department of Anesthesiology, Washington University School of MedicineSt. LouisUnited States
| | - Max B Kelz
- Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of PennsylvaniaPhiladelphiaUnited States
| |
Collapse
|
3
|
Ou M, Kuo FS, Chen X, Kahanovitch U, Olsen ML, Du G, Mulkey DK. Isoflurane inhibits a Kir4.1/5.1-like conductance in neonatal rat brainstem astrocytes and recombinant Kir4.1/5.1 channels in a heterologous expression system. J Neurophysiol 2020; 124:740-749. [PMID: 32727273 PMCID: PMC7509298 DOI: 10.1152/jn.00358.2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 07/29/2020] [Accepted: 07/29/2020] [Indexed: 02/08/2023] Open
Abstract
All inhalation anesthetics used clinically including isoflurane can suppress breathing; since this unwanted side effect can persist during the postoperative period and complicate patient recovery, there is a need to better understand how isoflurane affects cellular and molecular elements of respiratory control. Considering that astrocytes in a brainstem region known as the retrotrapezoid nucleus (RTN) contribute to the regulation of breathing in response to changes in CO2/H+ (i.e., function as respiratory chemoreceptors), and astrocytes in other brain regions are highly sensitive to isoflurane, we wanted to determine whether and how RTN astrocytes respond to isoflurane. We found that RTN astrocytes in slices from neonatal rat pups (7-12 days postnatal) respond to clinically relevant levels of isoflurane by inhibition of a CO2/H+-sensitive Kir4.1/5.1-like conductance [50% effective concentration (EC50) = 0.8 mM or ~1.7%]. We went on to confirm that similar levels of isoflurane (EC50 = 0.53 mM or 1.1%) inhibit recombinant Kir4.1/5.1 channels but not homomeric Kir4.1 channels expressed in HEK293 cells. We also found that exposure to CO2/H+ occluded subsequent effects of isoflurane on both native and recombinant Kir4.1/5.1 currents. These results identify Kir4.1/5.1 channels in astrocytes as novel targets of isoflurane. These results suggest astrocyte Kir4.1/5.1 channels contribute to certain aspects of general anesthesia including altered respiratory control.NEW & NOTEWORTHY An unwanted side effect of isoflurane anesthesia is suppression of breathing. Despite this clinical significance, effects of isoflurane on cellular and molecular elements of respiratory control are not well understood. Here, we show that isoflurane inhibits heteromeric Kir4.1/5.1 channels in a mammalian expression system and a Kir4.1/5.1-like conductance in astrocytes in a brainstem respiratory center. These results identify astrocyte Kir4.1/5.1 channels as novel targets of isoflurane and potential substrates for altered respiratory control during isoflurane anesthesia.
Collapse
Affiliation(s)
- Mengchan Ou
- Department of Anesthesiology, West China Hospital, Sichuan University, Chengdu City, China
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut
| | - Fu-Shan Kuo
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut
| | - Xinnian Chen
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut
| | - Uri Kahanovitch
- School of Neuroscience, Virginia Polytechnic and State University, Blacksburg, Virginia
| | - Michelle L Olsen
- School of Neuroscience, Virginia Polytechnic and State University, Blacksburg, Virginia
| | - Guizhi Du
- Department of Anesthesiology, West China Hospital, Sichuan University, Chengdu City, China
| | - Daniel K Mulkey
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut
| |
Collapse
|
4
|
Guidera JA, Taylor NE, Lee JT, Vlasov KY, Pei J, Stephen EP, Mayo JP, Brown EN, Solt K. Sevoflurane Induces Coherent Slow-Delta Oscillations in Rats. Front Neural Circuits 2017; 11:36. [PMID: 28725184 PMCID: PMC5495862 DOI: 10.3389/fncir.2017.00036] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Accepted: 05/16/2017] [Indexed: 12/04/2022] Open
Abstract
Although general anesthetics are routinely administered to surgical patients to induce loss of consciousness, the mechanisms underlying anesthetic-induced unconsciousness are not fully understood. In rats, we characterized changes in the extradural EEG and intracranial local field potentials (LFPs) within the prefrontal cortex (PFC), parietal cortex (PC), and central thalamus (CT) in response to progressively higher doses of the inhaled anesthetic sevoflurane. During induction with a low dose of sevoflurane, beta/low gamma (12–40 Hz) power increased in the frontal EEG and PFC, PC and CT LFPs, and PFC–CT and PFC–PFC LFP beta/low gamma coherence increased. Loss of movement (LOM) coincided with an abrupt decrease in beta/low gamma PFC–CT LFP coherence. Following LOM, cortically coherent slow-delta (0.1–4 Hz) oscillations were observed in the frontal EEG and PFC, PC and CT LFPs. At higher doses of sevoflurane sufficient to induce loss of the righting reflex, coherent slow-delta oscillations were dominant in the frontal EEG and PFC, PC and CT LFPs. Dynamics similar to those observed during induction were observed as animals emerged from sevoflurane anesthesia. We conclude that the rat is a useful animal model for sevoflurane-induced EEG oscillations in humans, and that coherent slow-delta oscillations are a correlate of sevoflurane-induced behavioral arrest and loss of righting in rats.
Collapse
Affiliation(s)
- Jennifer A Guidera
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, BostonMA, United States.,Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, CambridgeMA, United States
| | - Norman E Taylor
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, BostonMA, United States.,Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, CambridgeMA, United States.,Department of Anaesthesia, Harvard Medical School, BostonMA, United States
| | - Justin T Lee
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, BostonMA, United States.,Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, CambridgeMA, United States
| | - Ksenia Y Vlasov
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, BostonMA, United States.,Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, CambridgeMA, United States
| | - JunZhu Pei
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, BostonMA, United States.,Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, CambridgeMA, United States
| | - Emily P Stephen
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, BostonMA, United States.,Institute for Medical Engineering and Science, Massachusetts Institute of Technology, CambridgeMA, United States
| | - J Patrick Mayo
- Department of Neurobiology, Duke University, DurhamNC, United States
| | - Emery N Brown
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, BostonMA, United States.,Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, CambridgeMA, United States.,Department of Anaesthesia, Harvard Medical School, BostonMA, United States.,Institute for Medical Engineering and Science, Massachusetts Institute of Technology, CambridgeMA, United States.,The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, CambridgeMA, United States
| | - Ken Solt
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, BostonMA, United States.,Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, CambridgeMA, United States.,Department of Anaesthesia, Harvard Medical School, BostonMA, United States
| |
Collapse
|
5
|
Erb TO, von Ungern-Sternberg BS, Moll J, Frei FJ. Impact of high concentrations of sevoflurane on laryngeal reflex responses. Paediatr Anaesth 2017; 27:282-289. [PMID: 28181336 DOI: 10.1111/pan.13062] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/31/2016] [Indexed: 01/07/2023]
Abstract
BACKGROUND Exaggerated defensive upper airway reflexes, particularly laryngospasm, may cause hypoxemic damage, especially in children. General clinical experience suggests that laryngeal reflex responses are more common under light levels of anesthesia, and previous clinical studies have shown an inverse correlation between laryngeal responsiveness and depth of hypnosis. However, this seems to be less obvious in children anesthetized with sevoflurane. The aim of this study was to assess the impact of high concentrations of sevoflurane on laryngeal and respiratory reflex responses in spontaneously breathing children. Accordingly, we tested the hypothesis that laryngeal and respiratory reflex responses were completely suppressed in spontaneously breathing children when anesthetized with sevoflurane 4.7% (=MACED95Intubation ) as compared with sevoflurane 2.5% (=1 MAC). METHODS In this prospective observational study, we tested the hypothesis that the incidence of laryngospasm evoked by laryngeal stimulation is diminished under high concentrations of sevoflurane. Following Ethics approval, trial registration, and informed consent, 40 children (3-7 years) scheduled for elective surgery participated in the trial. All children received sevoflurane 2.5% (1 MAC) and 4.7% (ED95Intubation ) in random order with 5-min equilibration between the states. Under both conditions, distilled water was sprayed under bronchoscopic view onto the larynx. Potential laryngeal and respiratory reflex responses were assessed offline by a blinded reviewer. RESULTS Laryngospasm (episodes lasting >10 s) occurred in 12/38 (32%) of the patients anesthetized with sevoflurane 2.5%, vs 7/38 (18%) in those anesthetized with sevoflurane 4.7% (difference: OR 3.5; 95% CI [0.72-16.84], P = 0.18). All other reflex responses (coughing, expiration reflexes, and spasmodic panting) were infrequent and were similar among the examined concentrations. CONCLUSION Against our hypothesis, laryngospasm could still be observed in 18% of children under the higher concentration of sevoflurane (4.7%, ED95Intubation ).
Collapse
Affiliation(s)
- Thomas O Erb
- Department of Anesthesia, University of Basel Children's Hospital, Basel, Switzerland
| | - Britta S von Ungern-Sternberg
- Department of Anaesthesia and Pain Management, Princess Margaret Hospital for Children, Perth, WA, Australia.,School of Medicine and Pharmacology, The University of Western Australia, Perth, WA, Australia
| | - Jens Moll
- Department of Anesthesia, University of Basel Children's Hospital, Basel, Switzerland
| | - Franz J Frei
- Department of Anesthesia, University of Basel Children's Hospital, Basel, Switzerland
| |
Collapse
|
6
|
Bunting KM, Nalloor RI, Vazdarjanova A. Influence of Isoflurane on Immediate-Early Gene Expression. Front Behav Neurosci 2016; 9:363. [PMID: 26793081 PMCID: PMC4709487 DOI: 10.3389/fnbeh.2015.00363] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Accepted: 12/15/2015] [Indexed: 11/14/2022] Open
Abstract
Background: Anterograde amnesia is a hallmark effect of volatile anesthetics. Isoflurane is known to affect both the translation and transcription of plasticity-associated genes required for normal memory formation in many brain regions. What is not known is whether isoflurane anesthesia prevents the initiation of transcription or whether it halts transcription already in progress. We tested the hypothesis that general anesthesia with isoflurane prevents learning-induced initiation of transcription of several memory-associated immediate-early genes (IEGs) correlated with amnesia; we also assessed whether it stops transcription initiated prior to anesthetic administration. Methods: Using a Tone Fear Conditioning paradigm, rats were trained to associate a tone with foot-shock. Animals received either no anesthesia, anesthesia immediately after training, or anesthesia before, during, and after training. Animals were either sacrificed after training or tested 24 h later for long-term memory. Using Cellular Compartment Analysis of Temporal Activity by Fluorescence in situ Hybridization (catFISH), we examined the percentage of neurons expressing the IEGs Arc/Arg3.1 and Zif268/Egr1/Ngfi-A/Krox-24 in the dorsal hippocampus, primary somatosensory cortex, and primary auditory cortex. Results: On a cellular level, isoflurane administered at high doses (general anesthesia) prevented initiation of transcription, but did not stop transcription of Arc and Zif268 mRNA initiated prior to anesthesia. On a behavioral level, the same level of isoflurane anesthesia produced anterograde amnesia for fear conditioning when administered before and during training, but did not produce retrograde amnesia when administered immediately after training. Conclusion: General anesthesia with isoflurane prevents initiation of learning-related transcription but does not stop ongoing transcription of two plasticity-related IEGs, Arc and Zif268, a pattern of disruption that parallels the effects of isoflurane on memory formation. Combined with published research on the effects of volatile anesthetics on memory in behaving animals, our data suggests that different levels of anesthesia affect memory via different mechanisms: general anesthesia prevents elevation of mRNA levels of Arc and Zif268 which are necessary for normal memory formation, while anesthesia at lower doses affects the strength of memory by affecting levels of plasticity-related proteins.
Collapse
Affiliation(s)
- Kristopher M Bunting
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, AugustaGA, USA; Vazdarjanova Lab, Research Department, Charlie Norwood VA Medical Center, AugustaGA, USA
| | - Rebecca I Nalloor
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, AugustaGA, USA; Vazdarjanova Lab, Research Department, Charlie Norwood VA Medical Center, AugustaGA, USA
| | - Almira Vazdarjanova
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, AugustaGA, USA; Vazdarjanova Lab, Research Department, Charlie Norwood VA Medical Center, AugustaGA, USA
| |
Collapse
|
7
|
Pavone KJ, Akeju O, Sampson AL, Ling K, Purdon PL, Brown EN. Nitrous oxide-induced slow and delta oscillations. Clin Neurophysiol 2016; 127:556-564. [PMID: 26118489 PMCID: PMC4675698 DOI: 10.1016/j.clinph.2015.06.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Revised: 06/02/2015] [Accepted: 06/03/2015] [Indexed: 01/24/2023]
Abstract
OBJECTIVES Switching from maintenance of general anesthesia with an ether anesthetic to maintenance with high-dose (concentration >50% and total gas flow rate >4 liters per minute) nitrous oxide is a common practice used to facilitate emergence from general anesthesia. The transition from the ether anesthetic to nitrous oxide is associated with a switch in the putative mechanisms and sites of anesthetic action. We investigated whether there is an electroencephalogram (EEG) marker of this transition. METHODS We retrospectively studied the ether anesthetic to nitrous oxide transition in 19 patients with EEG monitoring receiving general anesthesia using the ether anesthetic sevoflurane combined with oxygen and air. RESULTS Following the transition to nitrous oxide, the alpha (8-12 Hz) oscillations associated with sevoflurane dissipated within 3-12 min (median 6 min) and were replaced by highly coherent large-amplitude slow-delta (0.1-4 Hz) oscillations that persisted for 2-12 min (median 3 min). CONCLUSIONS Administration of high-dose nitrous oxide is associated with transient, large amplitude slow-delta oscillations. SIGNIFICANCE We postulate that these slow-delta oscillations may result from nitrous oxide-induced blockade of major excitatory inputs (NMDA glutamate projections) from the brainstem (parabrachial nucleus and medial pontine reticular formation) to the thalamus and cortex. This EEG signature of high-dose nitrous oxide may offer new insights into brain states during general anesthesia.
Collapse
Affiliation(s)
- Kara J Pavone
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA
| | - Oluwaseun Akeju
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA; Department of Anaesthesia, Harvard Medical School, Boston, MA, USA
| | - Aaron L Sampson
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA
| | - Kelly Ling
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA
| | - Patrick L Purdon
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA; Department of Anaesthesia, Harvard Medical School, Boston, MA, USA
| | - Emery N Brown
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA; Department of Anaesthesia, Harvard Medical School, Boston, MA, USA; Department of Brain and Cognitive Science, Massachusetts Institute of Technology, Cambridge, MA, USA; Harvard-Massachusetts Institute of Technology Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA, USA; Institute for Medical Engineering and Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA.
| |
Collapse
|
8
|
Zhou C, Liang P, Liu J, Ke B, Wang X, Li F, Li T, Bayliss DA, Chen X. HCN1 Channels Contribute to the Effects of Amnesia and Hypnosis but not Immobility of Volatile Anesthetics. Anesth Analg 2015; 121:661-666. [PMID: 26287296 DOI: 10.1213/ane.0000000000000830] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND Hyperpolarization-activated, cyclic nucleotide-gated (HCN) subtype 1 (HCN1) channels have been identified as targets of ketamine to produce hypnosis. Volatile anesthetics also inhibit HCN1 channels. However, the effects of HCN1 channels on volatile anesthetics in vivo are still elusive. This study uses global and conditional HCN1 knockout mice to evaluate how HCN1 channels affect the actions of volatile anesthetics. METHODS Minimum alveolar concentrations (MACs) of isoflurane and sevoflurane that induced immobility (MAC of immobility) and/or hypnosis (MAC of hypnosis) were determined in wild-type mice, global HCN1 knockout (HCN1) mice, HCN1 channel gene with 2 lox-P sites flanking a region of the fourth exon of HCN1 (HCN1) mice, and forebrain-selective HCN1 knockout (HCN1: cre) mice. Immobility of mice was defined as no purposeful reactions to tail-clamping stimulus, and hypnosis was defined as loss of righting reflex. The amnestic effects of isoflurane and sevoflurane were evaluated by fear-potentiated startle in these 4 strains of mice. RESULTS All MAC values were expressed as mean ± SEM. For MAC of immobility of isoflurane, no significant difference was found among wild-type, HCN1, HCN1, and HCN1: cre mice (all ~1.24%-1.29% isoflurane). For both HCN1 and HCN1: cre mice, the MAC of hypnosis for isoflurane (each ~1.05% isoflurane) was significantly increased over their nonknockout controls: HCN1 versus wild-type (0.86% ± 0.03%, P < 0.001) and HCN1: cre versus HCN1 mice (0.84% ± 0.03%, P < 0.001); no significant difference was found between HCN1 and HCN1: cre mice. For MAC of immobility of sevoflurane, no significant difference was found among wild-type, HCN1, HCN1, and HCN1: cre mice (all ~2.6%-2.7% sevoflurane). For both HCN1 and HCN1: cre mice, the MAC of hypnosis for sevoflurane (each ~1.90% sevoflurane) was significantly increased over their nonknockout controls: HCN1 versus wild-type (1.58% ± 0.05%, P < 0.001) and HCN1: cre versus HCN1 mice (1.56% ± 0.05%, P < 0.001). No significant difference was found between HCN1 and HCN1: cre mice. By fear-potentiated startle experiments, amnestic effects of isoflurane and sevoflurane were significantly attenuated in HCN1 and HCN1: cre mice (both P < 0.002 versus wild-type or HCN1 mice). No significant difference was found between HCN1 and HCN1: cre mice. CONCLUSIONS Forebrain HCN1 channels contribute to hypnotic and amnestic effects of volatile anesthetics, but HCN1 channels are not involved in the immobilizing actions of volatile anesthetics.
Collapse
Affiliation(s)
- Cheng Zhou
- Laboratory of Anesthesia & Critical Care Medicine, Translational Neuroscience Center, West China Hospital of Sichuan University, Chengdu, Sichuan, P.R. China
| | - Peng Liang
- Department of Anesthesiology, West China Hospital of Sichuan University, Chengdu, Sichuan, P.R. China
| | - Jin Liu
- Department of Anesthesiology and Laboratory of Anesthesia & Critical Care Medicine, Translational Neuroscience Center, West China Hospital of Sichuan University, Chengdu, Sichuan, P.R. China
| | - Bowen Ke
- Laboratory of Anesthesia & Critical Care Medicine, Translational Neuroscience Center, West China Hospital of Sichuan University, Chengdu, Sichuan, P.R. China
| | - Xiaojia Wang
- Department of Anesthesiology and Laboratory of Anesthesia & Critical Care Medicine, Translational Neuroscience Center, West China Hospital of Sichuan University, Chengdu, Sichuan, P.R. China
| | - Fengshan Li
- Laboratory of Anesthesia & Critical Care Medicine, Translational Neuroscience Center, West China Hospital of Sichuan University, Chengdu, Sichuan, P.R. China
| | - Tao Li
- Laboratory of Anesthesia & Critical Care Medicine, Translational Neuroscience Center, West China Hospital of Sichuan University, Chengdu, Sichuan, P.R. China
| | - Douglas A Bayliss
- Department of Pharmacology and Anesthesiology, University of Virginia, Charlottesville, Virginia
| | - Xiangdong Chen
- Laboratory of Anesthesia & Critical Care Medicine, Translational Neuroscience Center, West China Hospital of Sichuan University, Chengdu, Sichuan, P.R. China; Department of Anesthesiology, Union Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, P.R. China
| |
Collapse
|
9
|
Wilson LD, Verrall RE. A volumetric and NMR study of cyclodextrin-inhalation anesthetic complexes in aqueous solutions. CAN J CHEM 2015. [DOI: 10.1139/cjc-2014-0549] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The apparent molar volumes (Vϕ) of two anesthetics (halothane and forane) have been determined in water and in binary solvent (H2O + cyclodextrin) systems at 25 °C. The results show that the magnitudes of Vϕ are greater in ternary solutions than in the binary aqueous systems. The apparent molar volumes at infinite dilution (Vϕo) of halothane in ternary solutions are observed to depend on the following factors: (i) the magnitude of the binding constant (K1:1), (ii) the lipophilicity of the anesthetic, (iii) the mole ratio of the host/halothane system, and (iv) the topology (i.e., facial vs. inclusion) of the host/guest complex. The volumetric properties of the ternary systems have been analyzed in terms of the complexed and uncomplexed species by application of Young’s rule. The formation of 1:1 CD–halothane complexes was successfully modeled using a two-state model. The binding affinity of the various cyclodextrins toward halothane is listed in descending order as follows: DM-β-CD > HP-β-CD > β-CD > α-CD > TM-β-CD.
Collapse
Affiliation(s)
- Lee D. Wilson
- Department of Chemistry, University of Saskatchewan, 110 Science Place (Room 156), Saskatoon, SK S7N 5C9, Canada
- Department of Chemistry, University of Saskatchewan, 110 Science Place (Room 156), Saskatoon, SK S7N 5C9, Canada
| | - Ronald E. Verrall
- Department of Chemistry, University of Saskatchewan, 110 Science Place (Room 156), Saskatoon, SK S7N 5C9, Canada
- Department of Chemistry, University of Saskatchewan, 110 Science Place (Room 156), Saskatoon, SK S7N 5C9, Canada
| |
Collapse
|
10
|
Event-related functional magnetic resonance imaging of a low dose of dexmedetomidine that impairs long-term memory. Anesthesiology 2013; 117:981-95. [PMID: 22929730 DOI: 10.1097/aln.0b013e31826be467] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Work suggests the amnesia from dexmedetomidine (an α2-adrenergic agonist) is caused by a failure of information to be encoded into long-term memory and that dexmedetomidine might differentially affect memory for emotionally arousing material. We investigated these issues in humans using event-related neuroimaging to reveal alterations in brain activity and subsequent memory effects associated with drug exposure. METHODS Forty-eight healthy volunteers received a computer-controlled infusion of either placebo or low-dose dexmedetomidine (target = 0.15 ng/ml plasma) during neuroimaging while they viewed and rated 80 emotionally arousing (e.g., graphic war wound) and 80 nonarousing neutral (e.g., cup) pictures for emotional arousal content. Long-term picture memory was tested 4 days later without neuroimaging. Imaging data were analyzed for drug effects, emotional processing differences, and memory-related changes with statistical parametric mapping-8. RESULTS Dexmedetomidine impaired overall (mean ± SEM) picture memory (placebo: 0.58 ± 0.03 vs. dexmedetomidine: 0.45 ± 0.03, P = 0.001), but did not differentially modulate memory as a function of item arousal. Arousing pictures were better remembered for both groups. Dexmedetomidine had regionally heterogeneous effects on brain activity, primarily decreasing it in the cortex and increasing it in thalamic and posterior hippocampal regions. Nevertheless, a single subsequent memory effect for item memory common to both groups was identified only in the left hippocampus/amygdala. Much of this effect was found to be larger for the placebo than dexmedetomidine group. CONCLUSION Dexmedetomidine impaired long-term picture memory, but did not disproportionately block memory for emotionally arousing items. The memory impairment on dexmedetomidine corresponds with a weakened hippocampal subsequent memory effect.
Collapse
|
11
|
Anesthetic activation of central respiratory chemoreceptor neurons involves inhibition of a THIK-1-like background K(+) current. J Neurosci 2010; 30:9324-34. [PMID: 20610767 DOI: 10.1523/jneurosci.1956-10.2010] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
At surgical depths of anesthesia, inhalational anesthetics cause a loss of motor response to painful stimuli (i.e., immobilization) that is characterized by profound inhibition of spinal motor circuits. Yet, although clearly depressed, the respiratory motor system continues to provide adequate ventilation under these same conditions. Here, we show that isoflurane causes robust activation of CO(2)/pH-sensitive, Phox2b-expressing neurons located in the retrotrapezoid nucleus (RTN) of the rodent brainstem, in vitro and in vivo. In brainstem slices from Phox2b-eGFP mice, the firing of pH-sensitive RTN neurons was strongly increased by isoflurane, independent of prevailing pH conditions. At least two ionic mechanisms contributed to anesthetic activation of RTN neurons: activation of an Na(+)-dependent cationic current and inhibition of a background K(+) current. Single-cell reverse transcription-PCR analysis of dissociated green fluorescent protein-labeled RTN neurons revealed expression of THIK-1 (TWIK-related halothane-inhibited K(+) channel, K(2P)13.1), a channel that shares key properties with the native RTN current (i.e., suppression by inhalational anesthetics, weak rectification, inhibition by extracellular Na(+), and pH-insensitivity). Isoflurane also increased firing rate of RTN chemosensitive neurons in urethane-anesthetized rats, again independent of CO(2) levels. In these animals, isoflurane transiently enhanced activity of the respiratory system, an effect that was most prominent at low levels of respiratory drive and mediated primarily by an increase in respiratory frequency. These data indicate that inhalational anesthetics cause activation of RTN neurons, which serve an important integrative role in respiratory control; the increased drive provided by enhanced RTN neuronal activity may contribute, in part, to maintaining respiratory motor activity under immobilizing anesthetic conditions.
Collapse
|
12
|
Rau V, Iyer SV, Oh I, Chandra D, Harrison N, Eger EI, Fanselow MS, Homanics GE, Sonner JM. Gamma-aminobutyric acid type A receptor alpha 4 subunit knockout mice are resistant to the amnestic effect of isoflurane. Anesth Analg 2009; 109:1816-22. [PMID: 19923508 DOI: 10.1213/ane.0b013e3181bf6ae6] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND General anesthesia produces multiple end points including immobility, hypnosis, sedation, and amnesia. Tonic inhibition via gamma-aminobutyric acid type A receptors (GABA(A)-Rs) may play a role in mediating behavioral end points that are suppressed by low concentrations of anesthetics (e.g., hypnosis and amnesia). GABA(A)-Rs containing the alpha4 subunit are highly concentrated in the hippocampus and thalamus, and when combined with delta subunits they mediate tonic inhibition, which is sensitive to low concentrations of isoflurane. METHODS In this study, we used a GABA(A) alpha4 receptor knockout mouse line to evaluate the contribution of alpha4-containing GABA(A)-Rs to the effects of immobility, hypnosis, and amnesia produced by isoflurane. Knockout mice and their wild-type counterparts were assessed on 3 behavioral tests: conditional fear (to assess amnesia), loss of righting reflex (to assess hypnosis), and the minimum alveolar concentration of inhaled anesthetic necessary to produce immobility in response to noxious stimulation in 50% of subjects (to assess immobility). RESULTS Genetic inactivation of the alpha4 subunit reduced the amnestic effect of isoflurane, minimally affected loss of righting reflex, and had no effect on immobility. CONCLUSIONS These results lend support to the hypothesis that different sites of action mediate different anesthetic end points and suggest that alpha4-containing GABA(A)-Rs are important mediators of the amnestic effect of isoflurane on hippocampal-dependent declarative memory.
Collapse
Affiliation(s)
- Vinuta Rau
- Department of Anesthesia and Perioperative Care, University of California San Francisco, San Francisco, California 94143-0464, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
13
|
Rau V, Iyer SV, Oh I, Chandra D, Harrison N, Eger EI, Fanselow MS, Homanics GE, Sonner JM. Gamma-aminobutyric acid type A receptor alpha 4 subunit knockout mice are resistant to the amnestic effect of isoflurane. Anesth Analg 2009. [PMID: 19923508 DOI: 10.123/ane.0b013e3181bf6ae6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
BACKGROUND General anesthesia produces multiple end points including immobility, hypnosis, sedation, and amnesia. Tonic inhibition via gamma-aminobutyric acid type A receptors (GABA(A)-Rs) may play a role in mediating behavioral end points that are suppressed by low concentrations of anesthetics (e.g., hypnosis and amnesia). GABA(A)-Rs containing the alpha4 subunit are highly concentrated in the hippocampus and thalamus, and when combined with delta subunits they mediate tonic inhibition, which is sensitive to low concentrations of isoflurane. METHODS In this study, we used a GABA(A) alpha4 receptor knockout mouse line to evaluate the contribution of alpha4-containing GABA(A)-Rs to the effects of immobility, hypnosis, and amnesia produced by isoflurane. Knockout mice and their wild-type counterparts were assessed on 3 behavioral tests: conditional fear (to assess amnesia), loss of righting reflex (to assess hypnosis), and the minimum alveolar concentration of inhaled anesthetic necessary to produce immobility in response to noxious stimulation in 50% of subjects (to assess immobility). RESULTS Genetic inactivation of the alpha4 subunit reduced the amnestic effect of isoflurane, minimally affected loss of righting reflex, and had no effect on immobility. CONCLUSIONS These results lend support to the hypothesis that different sites of action mediate different anesthetic end points and suggest that alpha4-containing GABA(A)-Rs are important mediators of the amnestic effect of isoflurane on hippocampal-dependent declarative memory.
Collapse
Affiliation(s)
- Vinuta Rau
- Department of Anesthesia and Perioperative Care, University of California San Francisco, San Francisco, California 94143-0464, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
14
|
Ye JH, Sokol KA, Bhavsar U. Glycine receptors contribute to hypnosis induced by ethanol. Alcohol Clin Exp Res 2009; 33:1069-74. [PMID: 19382904 DOI: 10.1111/j.1530-0277.2009.00928.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
BACKGROUND Glycine is a major inhibitory neurotransmitter in the adult central nervous system (CNS), and its receptors (GlyRs) are well known for their effects in the spinal cord and the lower brainstem. Accumulating evidence indicates that GlyRs are more widely distributed in the CNS, including many supraspinal regions. Previous in vitro studies have demonstrated that ethanol potentiates the function of these brain GlyRs, yet the behavioral role of the brain GlyRs has not been well explored. METHODS Experiments were conducted in rats. The loss of righting reflex (LORR) was used as a marker of the hypnotic state. We compared the LORR induced by systematic administration of ethanol and of ketamine in the absence and presence of the selective glycine receptor antagonist strychnine. Ketamine is a general anesthetic that does not affect GlyRs. RESULTS Systemically administered (by intraperitoneal injection) ethanol and ketamine dose-dependently induced LORR in rats. Furthermore, systemically administered (by subcutaneous injection) strychnine dose-dependently reduced the percentage of rats exhibiting LORR induced by ethanol, increased the onset time, and decreased the duration of LORR. Strychnine had no effect, however, on the LORR induced by ketamine. CONCLUSIONS Given that hypnosis is caused by neuronal depression in upper brain areas, we therefore conclude that brain GlyRs contribute at least in part to the hypnosis induced by ethanol.
Collapse
Affiliation(s)
- Jiang H Ye
- The Department of Anesthesiology, University of Medicine and Dentistry of New Jersey, New Jersey Medical School, Newark, NJ 07103, USA.
| | | | | |
Collapse
|
15
|
Westphalen RI, Gomez RS, Hemmings HC. Nicotinic receptor-evoked hippocampal norepinephrine release is highly sensitive to inhibition by isoflurane. Br J Anaesth 2009; 102:355-60. [PMID: 19189985 DOI: 10.1093/bja/aen387] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Inhaled anaesthetics (IAs) produce multiple dose-dependent behavioural effects including amnesia, hypnosis, and immobility in response to painful stimuli that are mediated by distinct anatomical, cellular, and molecular mechanisms. Amnesia is produced at lower anaesthetic concentrations compared with hypnosis or immobility. Nicotinic acetylcholine receptors (nAChRs) modulate hippocampal neural network correlates of memory and are highly sensitive to IAs. Activation of hippocampal nAChRs stimulates the release of norepinephrine (NE), a neurotransmitter implicated in modulating hippocampal synaptic plasticity. We tested the hypothesis that IAs disrupt hippocampal synaptic mechanisms critical to memory by determining the effects of isoflurane on NE release from hippocampal nerve terminals. METHODS Isolated nerve terminals prepared from adult male Sprague-Dawley rat hippocampus were radiolabelled with [(3)H]NE and either [(14)C]GABA or [(14)C]glutamate and superfused at 37 degrees C. Release evoked by a 2 min pulse of 100 microM nicotine or 5 microM 4-aminopyridine was evaluated in the presence or absence of isoflurane and/or selective antagonists. RESULTS Nicotine-evoked NE release from rat hippocampal nerve terminals was nAChR- and Ca(2+)-dependent, involved both alpha7 and non-alpha7 subunit-containing nAChRs, and was partially dependent on voltage-gated Na(+) channel activation based on sensitivities to various antagonists. Isoflurane inhibited nicotine-evoked NE release (IC(50)=0.18 mM) more potently than depolarization-evoked NE release (IC(50)=0.27 mM, P=0.014), consistent with distinct presynaptic mechanisms of IA action. CONCLUSIONS Inhibition of hippocampal nAChR-dependent NE release by subanaesthetic concentrations of isoflurane supports a role in IA-induced amnesia.
Collapse
Affiliation(s)
- R I Westphalen
- Department of Anesthesiology, Weill Cornell Medical College, New York, NY 10021, USA
| | | | | |
Collapse
|
16
|
Chen X, Shu S, Kennedy DP, Willcox SC, Bayliss DA. Subunit-specific effects of isoflurane on neuronal Ih in HCN1 knockout mice. J Neurophysiol 2009; 101:129-40. [PMID: 18971302 PMCID: PMC2637007 DOI: 10.1152/jn.01352.2007] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2008] [Accepted: 10/21/2008] [Indexed: 01/07/2023] Open
Abstract
The ionic mechanisms that contribute to general anesthetic actions have not been elucidated, although increasing evidence has pointed to roles for subthreshold ion channels, such as the HCN channels underlying the neuronal hyperpolarization-activated cationic current (Ih). Here, we used conventional HCN1 knockout mice to test directly the contributions of specific HCN subunits to effects of isoflurane, an inhalational anesthetic, on membrane and integrative properties of motor and cortical pyramidal neurons in vitro. Compared with wild-type mice, residual Ih from knockout animals was smaller in amplitude and presented with HCN2-like properties. Inhibition of Ih by isoflurane previously attributed to HCN1 subunit-containing channels (i.e., a hyperpolarizing shift in half-activation voltage [V1/2]) was absent in neurons from HCN1 knockout animals; the remaining inhibition of current amplitude could be attributed to effects on residual HCN2 channels. We also found that isoflurane increased temporal summation of excitatory postsynaptic potentials (EPSPs) in cortical neurons from wild-type mice; this effect was predicted by simulation of anesthetic-induced dendritic Ih inhibition, which also revealed more prominent summation accompanying shifts in V1/2 (an HCN1-like effect) than decreased current amplitude (an HCN2-like effect). Accordingly, anesthetic-induced EPSP summation was not observed in cortical cells from HCN1 knockout mice. In wild-type mice, the enhanced synaptic summation observed with low concentrations of isoflurane contributed to a net increase in cortical neuron excitability. In summary, HCN channel subunits account for distinct anesthetic effects on neuronal membrane properties and synaptic integration; inhibition of HCN1 in cortical neurons may contribute to the synaptically mediated slow-wave cortical synchronization that accompanies anesthetic-induced hypnosis.
Collapse
Affiliation(s)
- Xiangdong Chen
- Department of Pharmacology, University of Virginia, Charlottesville, VA, USA.
| | | | | | | | | |
Collapse
|
17
|
Hypothesis: suppression of memory protein formation underlies anesthetic-induced amnesia. Anesthesiology 2008; 109:768-70. [PMID: 18946284 DOI: 10.1097/aln.0b013e31818aa6f2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
|
18
|
Colloc'h N, Sopkova-de Oliveira Santos J, Retailleau P, Vivarès D, Bonneté F, Langlois d'Estainto B, Gallois B, Brisson A, Risso JJ, Lemaire M, Prangé T, Abraini JH. Protein crystallography under xenon and nitrous oxide pressure: comparison with in vivo pharmacology studies and implications for the mechanism of inhaled anesthetic action. Biophys J 2006; 92:217-24. [PMID: 17028130 PMCID: PMC1697869 DOI: 10.1529/biophysj.106.093807] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In contrast with most inhalational anesthetics, the anesthetic gases xenon (Xe) and nitrous oxide (N(2)O) act by blocking the N-methyl-d-aspartate (NMDA) receptor. Using x-ray crystallography, we examined the binding characteristics of these two gases on two soluble proteins as structural models: urate oxidase, which is a prototype of a variety of intracellular globular proteins, and annexin V, which has structural and functional characteristics that allow it to be considered as a prototype for the NMDA receptor. The structure of these proteins complexed with Xe and N(2)O were determined. One N(2)O molecule or one Xe atom binds to the same main site in both proteins. A second subsite is observed for N(2)O in each case. The gas-binding sites are always hydrophobic flexible cavities buried within the monomer. Comparison of the effects of Xe and N(2)O on urate oxidase and annexin V reveals an interesting relationship with the in vivo pharmacological effects of these gases, the ratio of the gas-binding sites' volume expansion and the ratio of the narcotic potency being similar. Given these data, we propose that alterations of cytosolic globular protein functions by general anesthetics would be responsible for the early stages of anesthesia such as amnesia and hypnosis and that additional alterations of ion-channel membrane receptor functions are required for deeper effects that progress to "surgical" anesthesia.
Collapse
Affiliation(s)
- Nathalie Colloc'h
- Centre CYCERON, UMR 6185, Université de Caen--CNRS, 14074 Caen cedex, France
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Cheng VY, Martin LJ, Elliott EM, Kim JH, Mount HTJ, Taverna FA, Roder JC, MacDonald JF, Bhambri A, Collinson N, Wafford KA, Orser BA. Alpha5GABAA receptors mediate the amnestic but not sedative-hypnotic effects of the general anesthetic etomidate. J Neurosci 2006; 26:3713-20. [PMID: 16597725 PMCID: PMC6674127 DOI: 10.1523/jneurosci.5024-05.2006] [Citation(s) in RCA: 175] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A fundamental objective of anesthesia research is to identify the receptors and brain regions that mediate the various behavioral components of the anesthetic state, including amnesia, immobility, and unconsciousness. Using complementary in vivo and in vitro approaches, we found that GABAA receptors that contain the alpha5 subunit (alpha5GABAARs) play a critical role in amnesia caused by the prototypic intravenous anesthetic etomidate. Whole-cell recordings from hippocampal pyramidal neurons showed that etomidate markedly increased a tonic inhibitory conductance generated by alpha5GABAARs, whereas synaptic transmission was only slightly enhanced. Long-term potentiation (LTP) of field EPSPs recorded in CA1 stratum radiatum was reduced by etomidate in wild-type (WT) but not alpha5 null mutant (alpha5-/-) mice. In addition, etomidate impaired memory performance of WT but not alpha5-/- mice for spatial and nonspatial hippocampal-dependent learning tasks. The brain concentration of etomidate associated with memory impairment in vivo was comparable with that which increased the tonic inhibitory conductance and blocked LTP in vitro. The alpha5-/- mice did not exhibit a generalized resistance to etomidate, in that the sedative-hypnotic effects measured with the rotarod, loss of righting reflex, and spontaneous motor activity were similar in WT and alpha5-/- mice. Deletion of the alpha5 subunit of the GABAARs reduced the amnestic but not the sedative-hypnotic properties of etomidate. Thus, the amnestic and sedative-hypnotic properties of etomidate can be dissociated on the basis of GABAAR subtype pharmacology.
Collapse
|
20
|
Affiliation(s)
- Jason A Campagna
- Department of Anesthesia and Critical Care, Massachusetts General Hospital, Boston, MA 02114, USA
| | | | | |
Collapse
|
21
|
Zhang Y, Trudell JR, Mascia MP, Laster MJ, Gong DH, Harris RA, Eger EI. The Anesthetic Potencies of Alkanethiols for Rats: Relevance to Theories of Narcosis. Anesth Analg 2000. [DOI: 10.1213/00000539-200011000-00045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
|
22
|
Mascia MP, Gong DH, Eger EI, Harris RA. The Anesthetic Potency of Propanol and Butanol Versus Propanethiol and Butanethiol in α1 Wild Type and α1(S267Q) Glycine Receptors. Anesth Analg 2000. [DOI: 10.1213/00000539-200011000-00044] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
|
23
|
Belelli D, Pistis M, Peters JA, Lambert JJ. General anaesthetic action at transmitter-gated inhibitory amino acid receptors. Trends Pharmacol Sci 1999; 20:496-502. [PMID: 10603492 DOI: 10.1016/s0165-6147(99)01405-4] [Citation(s) in RCA: 107] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Research within the past decade has provided compelling evidence that anaesthetics can act directly as allosteric modulators of transmitter-gated ion channels. Recent comparative studies of the effects of general anaesthetics across a structurally homologous family of inhibitory amino acid receptors that includes mammalian GABAA, glycine and Drosophila RDL GABA receptors have provided new insights into the structural basis of anaesthetic action at transmitter-gated channels. In this article, the differential effects of general anaesthetics across inhibitory amino acid receptors and the potential relevance of such actions to general anaesthesia will be discussed.
Collapse
Affiliation(s)
- D Belelli
- Department of Pharmacology and Neuroscience, Ninewells Hospital and Medical School, University of Dundee, Dundee, UK DD1 9SY.
| | | | | | | |
Collapse
|
24
|
Mihalek RM, Banerjee PK, Korpi ER, Quinlan JJ, Firestone LL, Mi ZP, Lagenaur C, Tretter V, Sieghart W, Anagnostaras SG, Sage JR, Fanselow MS, Guidotti A, Spigelman I, Li Z, DeLorey TM, Olsen RW, Homanics GE. Attenuated sensitivity to neuroactive steroids in gamma-aminobutyrate type A receptor delta subunit knockout mice. Proc Natl Acad Sci U S A 1999; 96:12905-10. [PMID: 10536021 PMCID: PMC23157 DOI: 10.1073/pnas.96.22.12905] [Citation(s) in RCA: 410] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
gamma-Aminobutyric acid (GABA) type A receptors mediate fast inhibitory synaptic transmission and have been implicated in responses to sedative/hypnotic agents (including neuroactive steroids), anxiety, and learning and memory. Using gene targeting technology, we generated a strain of mice deficient in the delta subunit of the GABA type A receptors. In vivo testing of various behavioral responses revealed a strikingly selective attenuation of responses to neuroactive steroids, but not to other modulatory drugs. Electrophysiological recordings from hippocampal slices revealed a significantly faster miniature inhibitory postsynaptic current decay time in null mice, with no change in miniature inhibitory postsynaptic current amplitude or frequency. Learning and memory assessed with fear conditioning were normal. These results begin to illuminate the novel contributions of the delta subunit to GABA pharmacology and sedative/hypnotic responses and behavior and provide insights into the physiology of neurosteroids.
Collapse
Affiliation(s)
- R M Mihalek
- Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
25
|
Pistis M, Belelli D, McGurk K, Peters JA, Lambert JJ. Complementary regulation of anaesthetic activation of human (alpha6beta3gamma2L) and Drosophila (RDL) GABA receptors by a single amino acid residue. J Physiol 1999; 515 ( Pt 1):3-18. [PMID: 9925873 PMCID: PMC2269142 DOI: 10.1111/j.1469-7793.1999.003ad.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
1. The influence of a transmembrane (TM2) amino acid located at a homologous position in human beta1 (S290) and beta3 (N289) GABAA receptor subunits and the RDL GABA receptor of Drosophila (M314) upon allosteric regulation by general anaesthetics has been investigated. 2. GABA-evoked currents mediated by human wild-type (WT) alpha6beta3gamma2L or WT RDL GABA receptors expressed in Xenopus laevis oocytes were augmented by propofol or pentobarbitone. High concentrations of either anaesthetic directly activated alpha6beta3gamma2L, but not RDL, receptors. 3. GABA-evoked currents mediated by human mutant GABAA receptors expressing the RDL methionine residue (i.e. alpha6beta3N289Mgamma2L) were potentiated by propofol or pentobarbitone with approximately 2-fold reduced potency and, in the case of propofol, reduced maximal effect. Conspicuously, the mutant receptor was refractory to activation by either propofol or pentobarbitone. 4. Incorporation of the homologous GABAA beta1-subunit residue in the RDL receptor (i.e. RDLM314S) increased the potency, but not the maximal effect, of GABA potentiation by either propofol or pentobarbitone. Strikingly, either anaesthetic now activated the receptor, an effect confirmed for propofol utilizing expression of WT or mutant RDL subunits in Schnieder S2 cells. At RDL receptors expressing the homologous beta3-subunit residue (i.e. RDLM314N) the actions of propofol were similarly affected, whereas those of pentobarbitone were unaltered. 5. The results indicate that the identity of a homologous amino acid affects, in a complementary manner, the direct activation of human (alpha6beta3gamma2L) and RDL GABA receptors by structurally distinct general anaesthetics. Whether the crucial residue acts as a regulator of signal transduction or as a component of an anaesthetic binding site per se is discussed.
Collapse
Affiliation(s)
- M Pistis
- Neurosciences Institute, Department of Pharmacology and Neuroscience, Ninewells Hospital and Medical School, Dundee University, Dundee DD1 9SY, UK
| | | | | | | | | |
Collapse
|
26
|
Sirois JE, Pancrazio JJ, Lynch C, Bayliss DA. Multiple ionic mechanisms mediate inhibition of rat motoneurones by inhalation anaesthetics. J Physiol 1998; 512 ( Pt 3):851-62. [PMID: 9769427 PMCID: PMC2231236 DOI: 10.1111/j.1469-7793.1998.851bd.x] [Citation(s) in RCA: 95] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
1. We studied the effects of inhalation anaesthetics on the membrane properties of hypoglossal motoneurones in a neonatal rat brainstem slice preparation. 2. In current clamp, halothane caused a membrane hyperpolarization that was invariably associated with decreased input resistance; in voltage clamp, halothane induced an outward current and increased input conductance. Qualitatively similar results were obtained with isoflurane and sevoflurane. 3. The halothane current reversed near the predicted K+ equilibrium potential (EK) and was reduced in elevated extracellular K+ and in the presence of Ba2+ (2 mM). Moreover, the Ba2+-sensitive component of halothane current was linear and reversed near EK. The halothane current was not sensitive to glibenclamide or thyrotropin-releasing hormone (TRH). Therefore, the halothane current was mediated, in part, by activation of a Ba2+-sensitive K+ current distinct from the ATP- and neurotransmitter-sensitive K+ currents in hypoglossal motoneurones. 4. Halothane also inhibited Ih, a hyperpolarization-activated cationic current; this was primarily due to a decrease in the absolute amount of current, although halothane also caused a small, but statistically significant, shift in the voltage dependence of Ih activation. Extracellular Cs+ (3 mM) blocked Ih and a component of halothane-sensitive current with properties reminiscent of Ih. 5. A small component of halothane current, resistant to Ba2+ and Cs+, was observed in TTX-containing solutions at potentials depolarized to approximately -70 mV. Partial Na+ substitution by N-methyl-D-glucamine completely abolished this residual current, indicating that halothane also inhibited a TTX-resistant Na+ current active near rest potentials. 6. Thus, halothane activates a Ba2+-sensitive, relatively voltage-independent K+ current and inhibits both Ih and a TTX-insensitive persistent Na+ current in hypoglossal motoneurones. These effects of halothane decrease motoneuronal excitability and may contribute to the immobilization that accompanies inhalation anaesthesia.
Collapse
Affiliation(s)
- J E Sirois
- Department of Pharmacology, University of Virginia, Charlottesville, VA 22908, USA.
| | | | | | | |
Collapse
|