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Chuang CM, Chen CY, Yen PS, Wu CH, Shiao LR, Wong KL, Chan P, Leung YM. Propofol Causes Sustained Ca2+ Elevation in Endothelial Cells by Stimulating Ryanodine Receptor and Suppressing Plasmalemmal Ca2+ Pump. J Cardiovasc Pharmacol 2022; 79:749-757. [PMID: 35239284 DOI: 10.1097/fjc.0000000000001246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2021] [Accepted: 01/23/2022] [Indexed: 11/25/2022]
Abstract
ABSTRACT Propofol, a general anesthetic administered intravenously, may cause pain at the injection site. The pain is in part due to irritation of vascular endothelial cells. We here investigated the effects of propofol on Ca2+ transport and pain mediator release in human umbilical vein endothelial cells (EA.hy926). Propofol mobilized Ca2+ from cyclopiazonic acid (CPA)-dischargeable pool but did not cause Ca2+ release from the lysosomal Ca2+ stores. Propofol-elicited Ca2+ release was suppressed by 100 μM ryanodine, suggesting the participation of ryanodine receptor channels. Propofol did not affect ATP-triggered Ca2+ release but abolished the Ca2+ influx triggered by ATP; in addition, propofol also suppressed store-operated Ca2+ entry elicited by CPA. Ca2+ clearance during CPA-induced Ca2+ discharge was unaffected by a low Na+ (50 mM) extracellular solution, but strongly suppressed by 5 mM La3+ (an inhibitor of plasmalemmal Ca2+ pump), suggesting Ca2+ extrusion was predominantly through the plasmalemmal Ca2+ pump. Propofol mimicked the effect of La3+ in suppressing Ca2+ clearance. Propofol also stimulated release of pain mediators, namely, reactive oxygen species and bradykinin. Our data suggest propofol elicited Ca2+ release and repressed Ca2+ clearance, causing a sustained cytosolic [Ca2+]i elevation. The latter may cause reactive oxygen species and bradykinin release, resulting in pain.
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Affiliation(s)
- Chin-Min Chuang
- Department of Emergency Medicine, China Medical University Hospital, Taichung, Taiwan
| | - Cing-Yu Chen
- Department of Physiology, China Medical University, Taichung, Taiwan
| | - Pao-Sheng Yen
- Department of Radiology, Kuang Tien General Hospital, Shalu, Taichung, Taiwan
| | - Cheng-Hsun Wu
- Department of Anatomy, China Medical University, Taichung, Taiwan
| | - Lian-Ru Shiao
- Department of Physiology, China Medical University, Taichung, Taiwan
| | - Kar-Lok Wong
- Department of Anesthesiology, Kuang Tien General Hospital, Shalu, Taichung, Taiwan
- Department of Anesthesiology, University of Hong Kong, Hong Kong, China; and
| | - Paul Chan
- Division of Cardiovascular Medicine, Department of Internal Medicine, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan
| | - Yuk-Man Leung
- Department of Physiology, China Medical University, Taichung, Taiwan
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Mulkey DK, Olsen ML, Ou M, Cleary CM, Du G. Putative Roles of Astrocytes in General Anesthesia. Curr Neuropharmacol 2022; 20:5-15. [PMID: 33588730 PMCID: PMC9199541 DOI: 10.2174/1570159x19666210215120755] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 01/29/2021] [Accepted: 02/06/2021] [Indexed: 02/08/2023] Open
Abstract
General anesthetics are a mainstay of modern medicine, and although much progress has been made towards identifying molecular targets of anesthetics and neural networks contributing to endpoints of general anesthesia, our understanding of how anesthetics work remains unclear. Reducing this knowledge gap is of fundamental importance to prevent unwanted and life-threatening side-effects associated with general anesthesia. General anesthetics are chemically diverse, yet they all have similar behavioral endpoints, and so for decades, research has sought to identify a single underlying mechanism to explain how anesthetics work. However, this effort has given way to the 'multiple target hypothesis' as it has become clear that anesthetics target many cellular proteins, including GABAA receptors, glutamate receptors, voltage-independent K+ channels, and voltagedependent K+, Ca2+ and Na+ channels, to name a few. Yet, despite evidence that astrocytes are capable of modulating multiple aspects of neural function and express many anesthetic target proteins, they have been largely ignored as potential targets of anesthesia. The purpose of this brief review is to highlight the effects of anesthetic on astrocyte processes and identify potential roles of astrocytes in behavioral endpoints of anesthesia (hypnosis, amnesia, analgesia, and immobilization).
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Affiliation(s)
- Daniel K. Mulkey
- Department of Physiology and Neurobiology, University of Connecticut, StorrsCT, USA;,Address correspondence to this author at the Department of Physiology and Neurobiology, University of Connecticut, Storrs CT, USA; E-mail:
| | | | | | - Colin M. Cleary
- Department of Physiology and Neurobiology, University of Connecticut, StorrsCT, USA
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Zhang Y, Wu S, Xie L, Yu S, Zhang L, Liu C, Zhou W, Yu T. Ketamine Within Clinically Effective Range Inhibits Glutamate Transmission From Astrocytes to Neurons and Disrupts Synchronization of Astrocytic SICs. Front Cell Neurosci 2019; 13:240. [PMID: 31244607 PMCID: PMC6581012 DOI: 10.3389/fncel.2019.00240] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Accepted: 05/14/2019] [Indexed: 01/07/2023] Open
Abstract
Background Astrocytes are now considered as crucial modulators of neuronal synaptic transmission. General anesthetics have been found to inhibit astrocytic activities, but it is not clear whether general anesthetics within the clinical concentration range affects the astrocyte-mediated synaptic regulation. Methods The effects of propofol, dexmedetomidine, and ketamine within clinically effective ranges on the slow inward currents (SICs) were tested by using the whole-cell recording in acute prefrontal cortex (PFC) slice preparations of rats. Astrocytes culture and HPLC were used to measure the effects of different anesthetics on the glutamate release of astrocytes. Results Propofol and dexmedetomidine showed no significant effect on the amplitude or frequency of SICs. Ketamine was found to inhibit the frequency of SICs in a concentration-dependent manner. The SICs synchronization rate of paired neurons was inhibited by 30 μM ketamine (from 42.5 ± 1.4% to 9.6 ± 0.8%) and was abolished by 300 μM ketamine. The astrocytic glutamate release induced by DHPG, an agonist of astrocytic type I metabotropic glutamate receptors, was not affected by ketamine, and ifenprodil, a selective antagonist of GluN1/GluN2B receptor, blocked all SICs and enhanced the inhibitory effect of 30 μM ketamine on the frequency of SICs. Ketamine at low concentration (3 μM) could inhibit the frequency of SICs, not the miniature excitatory postsynaptic currents (mEPSCs), and the inhibition rate of SICs was significantly higher than mEPSCs with 30 μM ketamine (44.5 ± 3% inhibition vs. 28.3 ± 6% inhibition). Conclusion Our data indicated that ketamine, not propofol and dexmedetomidine, within clinical concentration range inhibits glutamatergic transmission from astrocytes to neurons, which is likely mediated by the extrasynaptic GluN1/GluN2B receptor activation.
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Affiliation(s)
- Yu Zhang
- Department of Anesthesiology, Affiliated Hospital of Zunyi Medical University, Guizhou, China.,The Key Laboratory of Anesthesia and Organ Protection, Zunyi Medical University, Guizhou, China
| | - Sisi Wu
- The Key Laboratory of Anesthesia and Organ Protection, Zunyi Medical University, Guizhou, China
| | - Liwei Xie
- The Key Laboratory of Anesthesia and Organ Protection, Zunyi Medical University, Guizhou, China
| | - Shouyang Yu
- The Key Laboratory of Brain Science, Zunyi Medical University, Guizhou, China
| | - Lin Zhang
- The Key Laboratory of Anesthesia and Organ Protection, Zunyi Medical University, Guizhou, China
| | - Chengxi Liu
- The Key Laboratory of Brain Science, Zunyi Medical University, Guizhou, China
| | - Wenjing Zhou
- The Key Laboratory of Anesthesia and Organ Protection, Zunyi Medical University, Guizhou, China
| | - Tian Yu
- The Key Laboratory of Anesthesia and Organ Protection, Zunyi Medical University, Guizhou, China
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Hondebrink L, Zwartsen A, Westerink RHS. Effect fingerprinting of new psychoactive substances (NPS): What can we learn from in vitro data? Pharmacol Ther 2017; 182:193-224. [PMID: 29097307 DOI: 10.1016/j.pharmthera.2017.10.022] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The use of new psychoactive substances (NPS) is increasing and currently >600 NPS have been reported. However, limited information on neuropharmacological and toxicological effects of NPS is available, hampering risk characterization. We reviewed the literature on the in vitro neuronal modes of action to obtain effect fingerprints of different classes of illicit drugs and NPS. The most frequently reported NPS were selected for review: cathinones (MDPV, α-PVP, mephedrone, 4-MEC, pentedrone, methylone), cannabinoids (JWH-018), (hallucinogenic) phenethylamines (4-fluoroamphetamine, benzofurans (5-APB, 6-APB), 2C-B, NBOMes (25B-NBOMe, 25C-NBOMe, 25I-NBOMe)), arylcyclohexylamines (methoxetamine) and piperazine derivatives (mCPP, TFMPP, BZP). Our effect fingerprints highlight the main modes of action for the different NPS studied, including inhibition and/or reversal of monoamine reuptake transporters (cathinones and non-hallucinogenic phenethylamines), activation of 5-HT2receptors (hallucinogenic phenethylamines and piperazines), activation of cannabinoid receptors (cannabinoids) and inhibition of NDMA receptors (arylcyclohexylamines). Importantly, we identified additional targets by relating reported effect concentrations to the estimated human brain concentrations during recreational use. These additional targets include dopamine receptors, α- and β-adrenergic receptors, GABAAreceptors and acetylcholine receptors, which may all contribute to the observed clinical symptoms following exposure. Additional data is needed as the number of NPS continues to increase. Also, the effect fingerprints we have obtained are still incomplete and suffer from a large variation in the reported effects and effect sizes. Dedicated in vitro screening batteries will aid in complementing specific effect fingerprints of NPS. These fingerprints can be implemented in the risk assessments of NPS that are necessary for eventual control measures to reduce Public Health risks.
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Affiliation(s)
- Laura Hondebrink
- Dutch Poisons Information Center (DPIC), University Medical Center Utrecht, Utrecht University, The Netherlands
| | - Anne Zwartsen
- Dutch Poisons Information Center (DPIC), University Medical Center Utrecht, Utrecht University, The Netherlands; Neurotoxicology Research Group, Division Toxicology, Institute for Risk Assessment Sciences (IRAS), Faculty of Veterinary Medicine, Utrecht University, P.O. Box 80.177, NL-3508 TD, Utrecht, The Netherlands
| | - Remco H S Westerink
- Neurotoxicology Research Group, Division Toxicology, Institute for Risk Assessment Sciences (IRAS), Faculty of Veterinary Medicine, Utrecht University, P.O. Box 80.177, NL-3508 TD, Utrecht, The Netherlands.
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Zhao Y, Liu B, Wang Q, Yuan D, Yang Y, Hong X, Wang X, Tao L. Propofol depresses the cytotoxicity of X-ray irradiation through inhibition of gap junctions. Anesth Analg 2011; 112:1088-95. [PMID: 21415436 DOI: 10.1213/ane.0b013e31820f288e] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND General anesthetics (e.g., propofol) influence the therapeutic activity of intraoperative radiotherapy but the mechanism of the effects is largely unknown. It has been reported that propofol inhibits gap junction (GJ) function briefly, and a functional GJ enhances the efficacy of radiotherapy in some cancer cells. Yet the mechanisms underlying the inhibition of GJ function by propofol and the influence of propofol on therapeutic activity of intraoperative radiotherapy are unknown. METHODS The role of propofol at clinically relevant concentrations in the modulation of radiograph-induced cytotoxicity in HeLa cells transfected with connexin 32 (Cx32) plasmid was explored by manipulation of connexin expression, GJ presence, and function. GJ function, Cx32 protein level, and Cx32 mRNA expression were determined by "Parachute" dye-coupling assay, Western blotting, and reverse transcriptase-polymerase chain reaction, respectively. RESULTS Propofol significantly reduced radiograph-induced cytotoxicity only in the presence of functional GJ. Four-hour propofol exposure inhibited GJ function mainly by diminution of Cx32 protein levels but without influence on Cx32 mRNA expression. CONCLUSIONS These results suggest that propofol inhibits the function of the GJ through the reduction of Cx32 protein levels by a transcription-independent mechanism. They further indicate that propofol depresses the cytotoxicity of radiograph irradiation through inhibition of GJ activity.
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Affiliation(s)
- Yuping Zhao
- Department of Anaesthesia, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, People's Republic of China
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Wentlandt K, Samoilova M, Carlen PL, El Beheiry H. General anesthetics inhibit gap junction communication in cultured organotypic hippocampal slices. Anesth Analg 2006; 102:1692-8. [PMID: 16717311 DOI: 10.1213/01.ane.0000202472.41103.78] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Gap junctions are protein channels that directly connect the cytosol of neighboring cells, thus forming electrical synapses and promoting synchronous neuronal activities. Such activities lead to the initiation and propagation of electroencephalogram oscillations implicated in cognition and consciousness. In this study, we investigated the effects of propofol, thiopental, and halothane on gap junction communication in cultured organotypic hippocampal slices by recovery of fluorescence after photo bleaching (FRAP) technique and electrophysiological recordings. Propofol 15 microM and thiopental 10 microM attenuated gap junction communication in slice cultures by 46.7% +/- 4.5% and 48.8% +/- 5.5%, respectively, as measured by FRAP. Smaller concentrations of propofol 5 microM and thiopental 2 microM did not change gap junction coupling. Accompanying the decreased gap junction communication, hippocampus slice cultures exposed to propofol 15 microM and thiopental 10 microM were found to have reduced electrophysiologic spontaneous discharges and primary after discharges evoked by a tetanic train of 50 Hz for 2 s. On the other hand, halothane 0.64 mM, a concentration slightly larger than twice its minimum alveolar concentration had no effect on gap junction coupling while halothane 2.8 mM blocked FRAP by 70%. The current study illustrates that anesthetic concentrations of propofol and thiopental, but not halothane, attenuate gap junction communication in cultured hippocampal slices. Suppression of gap junction function could compound the mechanisms of anesthetic actions.
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Affiliation(s)
- Kirsten Wentlandt
- Division of Cellular and Molecular Biology, Toronto Western Research Institute, Department of Anesthesia & Pain Management, Physiology, University of Toronto, University Health Network, Toronto, Ontario, Canada
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Wentlandt K, Carlen PL, Kushnir M, Naus CC, El-Beheiry H. General anesthetics attenuate gap junction coupling in P19 cell line. J Neurosci Res 2005; 81:746-52. [PMID: 15971264 DOI: 10.1002/jnr.20577] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Gap junction communication is widespread throughout the mammalian nervous system among neurons as well as glia. We addressed the hypothesis that general anesthetics attenuate gap junction mediated coupling in P19 cell line that can differentiate into neuronal-like cells and astrocytes and oligodendrocytes. We characterized the extent of dye coupling over time in the P19 cell line using colocalization of chlormethylbenzamido-1,1 dioctadecyl-3,3,3',3'-tetramethylindocarbocyamine (CM-DiI) and calcein-AM in donor and recipient cells in cocultures. After seeding, the gap junction permeant dye calcein spreads from donor to recipient cells. CM-DiI and calcein fluorescence identified donor and recipient cells, respectively. The extent of intercellular connections was evaluated using cell counting and flow cytometry up to 2 hr after treatment. Clinically relevant concentrations of the intravenous anesthetics propofol (15 microM) and thiopental (10 microM) attenuated gap junction permeability in P19 cell cultures. In contrast, halothane, a volatile anesthetic in a concentration (0.64 mM) relevant to its free aqueous EC50 had no effect on gap junction coupling; however, very high halothane concentrations (2.8 mM) blocked dye transfer by approximately 90%. The results indicate that halothane concentrations pertinent to clinical anesthesia were unable to attenuate gap junction communication in a cell line that can express neuronal and glial gap junction proteins; however, clinically relevant concentrations of propofol and thiopental depressed gap junction coupling.
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Affiliation(s)
- Kirsten Wentlandt
- University Health Network, Toronto Western Research Institute, Division of Cellular and Molecular Biology, Toronto, Ontario, Canada
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Woodall AJ, McCrohan CR. Excitatory actions of propofol and ketamine in the snail Lymnaea stagnalis. Comp Biochem Physiol C Toxicol Pharmacol 2000; 127:297-305. [PMID: 11246501 DOI: 10.1016/s0742-8413(00)00155-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This study compares the actions of the intravenous anaesthetics propofol and ketamine on animal behaviour and neuronal activity in the snail Lymnaea stagnalis, particularly in relation to excitatory effects observed clinically. When injected into the whole animal, neither agent induced total anaesthesia. Rather, behavioural activity was enhanced by propofol (10(-5) M) and ketamine (10(-7) M), indicating excitatory effects. When superfused over the isolated central nervous system (CNS), differential effects were produced in two identified neurons, right pedal dorsal 1 (RPeD1) and visceral dorsal 4 (VD4). Resting membrane properties were largely unaffected. However, spike after hyperpolarisation was significantly reduced in RPeD1, but not VD4, with some evidence of increased excitability. In addition, an intrinsic bursting property (post-stimulus burst) in VD4 was altered by propofol (10(-7) M). The results suggest significant excitatory components in the actions of some intravenous anaesthetics, as well as a potential role in modifying excitation and bursting mechanisms in the CNS.
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Affiliation(s)
- A J Woodall
- School of Biological Sciences, University of Manchester, UK
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Gilliland HE, Armstrong MA, Carabine U, McMurray TJ. The choice of anesthetic maintenance technique influences the antiinflammatory cytokine response to abdominal surgery. Anesth Analg 1997. [PMID: 9390615 DOI: 10.1213/00000539-199712000-00039] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
UNLABELLED Outcome in some diseases is determined by the relationship between pro- and antiinflammatory cytokines. Surgery may also provoke a cytokine response, which has both pro- and antiinflammatory components. The aim of this study was to ascertain whether anesthetic technique can modify the balance of cytokines associated with abdominal surgery. Twenty patients scheduled to undergo elective abdominal hysterectomy were randomly allocated to receive maintenance of anesthesia with isoflurane (IH group) or propofol (IV group). Venous blood samples for measurement of tumor necrosis factor alpha (TNF-alpha), interleukin-6 (IL-6), interleukin-10 (IL-10), and interleukin-1 receptor antagonist (IL-1ra) were taken before the induction of anesthesia and at set intervals until 24 h postoperatively. TNF-alpha levels remained low throughout the study; however, all patients showed a significant postoperative increase in IL-6, IL-10, and IL-1ra (P < 0.05). Levels of the proinflammatory cytokine IL-6 were similar in both groups, whereas the antiinflammatory cytokine IL-10 was higher in the IV group at 4 h postoperatively (P < 0.02). The difference between groups in terms of IL-1ra production just failed to reach significance (P < 0.06). We conclude that the cytokine response to abdominal surgery has both pro- and antiinflammatory components and that the choice of anesthetic may modify the balance of these cytokines. IMPLICATIONS This study demonstrates that in addition to the widely reported proinflammatory cytokine response, elective abdominal surgery provokes an antiinflammatory response, which may be enhanced by total intravenous anesthesia. The ability of anesthetics to modify the cytokine response to surgery may have therapeutic potential.
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Affiliation(s)
- H E Gilliland
- Department of Clinical Anaesthesia, Royal Victoria Hospital, Belfast, Northern Ireland
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Gilliland HE, Armstrong MA, Carabine U, McMurray TJ. The choice of anesthetic maintenance technique influences the antiinflammatory cytokine response to abdominal surgery. Anesth Analg 1997; 85:1394-8. [PMID: 9390615 DOI: 10.1097/00000539-199712000-00039] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
UNLABELLED Outcome in some diseases is determined by the relationship between pro- and antiinflammatory cytokines. Surgery may also provoke a cytokine response, which has both pro- and antiinflammatory components. The aim of this study was to ascertain whether anesthetic technique can modify the balance of cytokines associated with abdominal surgery. Twenty patients scheduled to undergo elective abdominal hysterectomy were randomly allocated to receive maintenance of anesthesia with isoflurane (IH group) or propofol (IV group). Venous blood samples for measurement of tumor necrosis factor alpha (TNF-alpha), interleukin-6 (IL-6), interleukin-10 (IL-10), and interleukin-1 receptor antagonist (IL-1ra) were taken before the induction of anesthesia and at set intervals until 24 h postoperatively. TNF-alpha levels remained low throughout the study; however, all patients showed a significant postoperative increase in IL-6, IL-10, and IL-1ra (P < 0.05). Levels of the proinflammatory cytokine IL-6 were similar in both groups, whereas the antiinflammatory cytokine IL-10 was higher in the IV group at 4 h postoperatively (P < 0.02). The difference between groups in terms of IL-1ra production just failed to reach significance (P < 0.06). We conclude that the cytokine response to abdominal surgery has both pro- and antiinflammatory components and that the choice of anesthetic may modify the balance of these cytokines. IMPLICATIONS This study demonstrates that in addition to the widely reported proinflammatory cytokine response, elective abdominal surgery provokes an antiinflammatory response, which may be enhanced by total intravenous anesthesia. The ability of anesthetics to modify the cytokine response to surgery may have therapeutic potential.
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Affiliation(s)
- H E Gilliland
- Department of Clinical Anaesthesia, Royal Victoria Hospital, Belfast, Northern Ireland
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Li YC, Ridefelt P, Wiklund L, Bjerneroth G. Propofol induces a lowering of free cytosolic calcium in myocardial cells. Acta Anaesthesiol Scand 1997; 41:633-8. [PMID: 9181167 DOI: 10.1111/j.1399-6576.1997.tb04756.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND The intravenous anaesthetic drug propofol has been shown to depress myocardial contractility. Ketamine, on the other hand, is a well-documented cardiovascular stimulant. These differences could possibly be due to different effects of the drugs on the calcium homeostasis of the myocardium. METHODS The fluorescent intracellular probe fura-2 acetoxymethyl ester (fura-2/AM) was used in this in vitro investigation to study the influence of intravenous anaesthetic drugs on free cytosolic calcium concentration in suspensions of isolated rat myocardial cells. RESULTS Addition of 0.5-2.0 micrograms/mL propofol resulted in a significant and dose-dependent decrease of free cytosolic calcium concentration in the myocardial cells, while addition of 0.25-2.5 micrograms/mL ketamine did not affect this concentration significantly. CONCLUSION The results imply that the previously demonstrated negative inotropic effect of propofol could possibly be related to its influence on calcium availability in the myocardium.
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Affiliation(s)
- Y C Li
- Department of Anaesthesiology, Uppsala University Hospital, Sweden
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