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Pardo-Valencia J, Moreno-Gomez M, Mercado N, Pro B, Ammann C, Humanes-Valera D, Foffani G. Local wakefulness-like activity of layer 5 cortex under general anaesthesia. J Physiol 2024. [PMID: 39316039 DOI: 10.1113/jp286417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2024] [Accepted: 08/08/2024] [Indexed: 09/25/2024] Open
Abstract
Consciousness, defined as being aware of and responsive to one's surroundings, is characteristic of normal waking life and typically is lost during sleep and general anaesthesia. The traditional view of consciousness as a global brain state has evolved toward a more sophisticated interplay between global and local states, with the presence of local sleep in the awake brain and local wakefulness in the sleeping brain. However, this interplay is not clear for general anaesthesia, where loss of consciousness was recently suggested to be associated with a global state of brain-wide synchrony that selectively involves layer 5 cortical pyramidal neurons across sensory, motor and associative areas. According to this global view, local wakefulness of layer 5 cortex should be incompatible with deep anaesthesia, a hypothesis that deserves to be scrutinised with causal manipulations. Here, we show that unilateral chemogenetic activation of layer 5 pyramidal neurons in the sensorimotor cortex of isoflurane-anaesthetised mice induces a local state transition from slow-wave activity to tonic firing in the transfected hemisphere. This wakefulness-like activity dramatically disrupts layer 5 interhemispheric synchrony with mirror-image locations in the contralateral hemisphere, but does not reduce the level of unconsciousness under deep anaesthesia, nor in the transitions to/from anaesthesia. Global layer 5 synchrony may thus be a sufficient condition for anaesthesia-induced unconsciousness, but is not a necessary one, at least under isoflurane anaesthesia. Local wakefulness-like activity of layer 5 cortex can be induced and maintained under deep anaesthesia, encouraging further investigation into the local vs. global aspects of anaesthesia-induced unconsciousness. KEY POINTS: The neural correlates of consciousness have evolved from global brain states to a nuanced interplay between global and local states, evident in terms of local sleep in awake brains and local wakefulness in sleeping brains. The concept of local wakefulness remains unclear for general anaesthesia, where the loss of consciousness has been recently suggested to involve brain-wide synchrony of layer 5 cortical neurons. We found that local wakefulness-like activity of layer 5 cortical can be chemogenetically induced in anaesthetised mice without affecting the depth of anaesthesia or the transitions to and from unconsciousness. Global layer 5 synchrony may thus be a sufficient but not necessary feature for the unconsciousness induced by general anaesthesia. Local wakefulness-like activity of layer 5 neurons is compatible with general anaesthesia, thus promoting further investigation into the local vs. global aspects of anaesthesia-induced unconsciousness.
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Affiliation(s)
- Jesús Pardo-Valencia
- HM CINAC (Centro Integral de Neurociencias Abarca Campal), Hospital Universitario HM Puerta del Sur, HM Hospitales, Madrid, Spain
- Escuela Técnica Superior de Ingenieros de Telecomunicación, Universidad Politécnica de Madrid, Madrid, Spain
- Instituto de Investigación Sanitaria HM Hospitales, Spain
| | - Miryam Moreno-Gomez
- HM CINAC (Centro Integral de Neurociencias Abarca Campal), Hospital Universitario HM Puerta del Sur, HM Hospitales, Madrid, Spain
- Instituto de Investigación Sanitaria HM Hospitales, Spain
- PhD Program in Neuroscience, Universidad Autonoma de Madrid-Cajal Institute, Madrid, Spain
| | - Noelia Mercado
- HM CINAC (Centro Integral de Neurociencias Abarca Campal), Hospital Universitario HM Puerta del Sur, HM Hospitales, Madrid, Spain
- Instituto de Investigación Sanitaria HM Hospitales, Spain
| | - Beatriz Pro
- HM CINAC (Centro Integral de Neurociencias Abarca Campal), Hospital Universitario HM Puerta del Sur, HM Hospitales, Madrid, Spain
- Instituto de Investigación Sanitaria HM Hospitales, Spain
| | - Claudia Ammann
- HM CINAC (Centro Integral de Neurociencias Abarca Campal), Hospital Universitario HM Puerta del Sur, HM Hospitales, Madrid, Spain
- Instituto de Investigación Sanitaria HM Hospitales, Spain
- Facultad HM de Ciencias de la Salud, Universidad Camilo José Cela, Madrid, Spain
| | - Desire Humanes-Valera
- HM CINAC (Centro Integral de Neurociencias Abarca Campal), Hospital Universitario HM Puerta del Sur, HM Hospitales, Madrid, Spain
- Instituto de Investigación Sanitaria HM Hospitales, Spain
| | - Guglielmo Foffani
- HM CINAC (Centro Integral de Neurociencias Abarca Campal), Hospital Universitario HM Puerta del Sur, HM Hospitales, Madrid, Spain
- Instituto de Investigación Sanitaria HM Hospitales, Spain
- Hospital Nacional de Parapléjicos, SESCAM, Toledo, Spain
- CIBERNED, Instituto de Salud Carlos III, Madrid, Spain
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Tomsits P, Volz L, Xia R, Chivukula A, Schüttler D, Clauß S. Medetomidine/midazolam/fentanyl narcosis alters cardiac autonomic tone leading to conduction disorders and arrhythmias in mice. Lab Anim (NY) 2023; 52:85-92. [PMID: 36959339 PMCID: PMC10063441 DOI: 10.1038/s41684-023-01141-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 02/15/2023] [Indexed: 03/25/2023]
Abstract
Arrhythmias are critical contributors to cardiovascular morbidity and mortality. Therapies are mainly symptomatic and often insufficient, emphasizing the need for basic research to unveil the mechanisms underlying arrhythmias and to enable better and ideally causal therapies. In translational approaches, mice are commonly used to study arrhythmia mechanisms in vivo. Experimental electrophysiology studies in mice are performed under anesthesia with medetomidine/midazolam/fentanyl (MMF) and isoflurane/fentanyl (IF) as commonly used regimens. Despite evidence of adverse effects of individual components on cardiac function, few data are available regarding the specific effects of these regimens on cardiac electrophysiology in mice. Here we present a study investigating the effects of MMF and IF narcosis on cardiac electrophysiology in vivo in C57BL/6N wild-type mice. Telemetry transmitters were implanted in a group of mice, which served as controls for baseline parameters without narcosis. In two other groups of mice, electrocardiogram and invasive electrophysiology studies were performed under narcosis (with either MMF or IF). Basic electrocardiogram parameters, heart rate variability parameters, sinus node and atrioventricular node function, and susceptibility to arrhythmias were assessed. Experimental data suggest a remarkable influence of MMF on cardiac electrophysiology compared with IF and awake animals. While IF only moderately reduced heart rate, MMF led to significant bradycardia, spontaneous arrhythmias, heart rate variability alterations as well as sinus and AV node dysfunction, and increased inducibility of ventricular arrhythmias. On the basis of these observed effects, we suggest avoiding MMF in mice, specifically when studying cardiac electrophysiology, but also whenever a regular heartbeat is required for reliable results, such as in heart failure or imaging research.
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Affiliation(s)
- Philipp Tomsits
- Medizinische Klinik und Poliklinik I, University Hospital Munich, Campus Grosshadern and Innenstadt, Ludwig-Maximilians University Munich (LMU), Munich, Germany.
- DZHK (German Centre for Cardiovascular Research), Partner Site Munich, Munich Heart Alliance (MHA), Munich, Germany.
- Institute of Surgical Research at the Walter-Brendel-Centre of Experimental Medicine, University Hospital, LMU Munich, Munich, Germany.
| | - Lina Volz
- Medizinische Klinik und Poliklinik I, University Hospital Munich, Campus Grosshadern and Innenstadt, Ludwig-Maximilians University Munich (LMU), Munich, Germany
- DZHK (German Centre for Cardiovascular Research), Partner Site Munich, Munich Heart Alliance (MHA), Munich, Germany
- Institute of Surgical Research at the Walter-Brendel-Centre of Experimental Medicine, University Hospital, LMU Munich, Munich, Germany
| | - Ruibing Xia
- Medizinische Klinik und Poliklinik I, University Hospital Munich, Campus Grosshadern and Innenstadt, Ludwig-Maximilians University Munich (LMU), Munich, Germany
- Institute of Surgical Research at the Walter-Brendel-Centre of Experimental Medicine, University Hospital, LMU Munich, Munich, Germany
| | - Aparna Chivukula
- Medizinische Klinik und Poliklinik I, University Hospital Munich, Campus Grosshadern and Innenstadt, Ludwig-Maximilians University Munich (LMU), Munich, Germany
- DZHK (German Centre for Cardiovascular Research), Partner Site Munich, Munich Heart Alliance (MHA), Munich, Germany
- Institute of Surgical Research at the Walter-Brendel-Centre of Experimental Medicine, University Hospital, LMU Munich, Munich, Germany
| | - Dominik Schüttler
- Medizinische Klinik und Poliklinik I, University Hospital Munich, Campus Grosshadern and Innenstadt, Ludwig-Maximilians University Munich (LMU), Munich, Germany
- DZHK (German Centre for Cardiovascular Research), Partner Site Munich, Munich Heart Alliance (MHA), Munich, Germany
- Institute of Surgical Research at the Walter-Brendel-Centre of Experimental Medicine, University Hospital, LMU Munich, Munich, Germany
| | - Sebastian Clauß
- Medizinische Klinik und Poliklinik I, University Hospital Munich, Campus Grosshadern and Innenstadt, Ludwig-Maximilians University Munich (LMU), Munich, Germany.
- DZHK (German Centre for Cardiovascular Research), Partner Site Munich, Munich Heart Alliance (MHA), Munich, Germany.
- Institute of Surgical Research at the Walter-Brendel-Centre of Experimental Medicine, University Hospital, LMU Munich, Munich, Germany.
- Interfaculty Center for Endocrine and Cardiovascular Disease Network Modelling and Clinical Transfer (ICONLMU), LMU Munich, Munich, Germany.
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Poon YY, Liu YW, Huang YH, Chan SHH, Tsai CY. Postoperative Stroke after Spinal Anesthesia and Responses of Carotid or Cerebral Blood Flow and Baroreflex Functionality to Spinal Bupivacaine in Rats. BIOLOGY 2021; 10:biology10070617. [PMID: 34356472 PMCID: PMC8301092 DOI: 10.3390/biology10070617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 06/25/2021] [Accepted: 07/01/2021] [Indexed: 11/16/2022]
Abstract
Spinal anesthesia is generally accepted as an effective and safe practice. Three rare incidents of postoperative cerebral infarction after surgery under spinal anesthesia prompted us to assess whether spinal bupivacaine may compromise carotid or cerebral blood flow. Postoperative examination after the stroke incident revealed that all three patients shared a common pathology of stenosis or atheromatosis in the carotid or middle cerebral artery. In a companion study using 69 Sprague-Dawley rats, subarachnoid application of bupivacaine elicited an initial (Phase I) reduction in the mean arterial pressure, carotid blood flow (CBF) and baroreflex-mediated sympathetic vasomotor tone, all of which subsequently returned to baseline (Phase II). Whereas heart rate (HR) exhibited sustained reduction, cardiac vagal baroreflex, baroreflex efficiency index (BEI) and tissue perfusion and oxygen in the cerebral cortex remained unaltered. However, in one-third of the rats studied, Phase II gave way to Phase III characterized by secondary hypotension and depressed baroreflex-mediated sympathetic vasomotor tone, along with declined HR, sustained cardiac vagal baroreflex, decreased BEI, reduced CBF and waning tissue perfusion or oxygen in the cerebral cortex. We concluded that carotid and cerebral blood flow can indeed be compromised after spinal anesthesia, and an impaired baroreflex-mediated sympathetic vasomotor tone, which leads to hypotension, plays a contributory role.
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Affiliation(s)
- Yan-Yuen Poon
- Department of Anesthesiology, Chang Gung Memorial Hospital, Kaohsiung 83301, Taiwan;
- Institute for Translational Research in Biomedicine, Chang Gung Memorial Hospital, Kaohsiung 83301, Taiwan;
| | - Yueh-Wei Liu
- Department of General Surgery, Chang Gung Memorial Hospital, Kaohsiung 83301, Taiwan;
| | - Ya-Hui Huang
- Institute for Translational Research in Biomedicine, Chang Gung Memorial Hospital, Kaohsiung 83301, Taiwan;
| | - Samuel H. H. Chan
- Institute for Translational Research in Biomedicine, Chang Gung Memorial Hospital, Kaohsiung 83301, Taiwan;
- Correspondence: (S.H.H.C.); (C.-Y.T.)
| | - Ching-Yi Tsai
- Institute for Translational Research in Biomedicine, Chang Gung Memorial Hospital, Kaohsiung 83301, Taiwan;
- Correspondence: (S.H.H.C.); (C.-Y.T.)
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