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Das D, Wong A, Friedman TN, Kerr BJ, Kurata HT, Lamothe SM. Reducing agents facilitate membrane patch seal integrity and longevity. Channels (Austin) 2024; 18:2297621. [PMID: 38154061 PMCID: PMC10761044 DOI: 10.1080/19336950.2023.2297621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2023] Open
Abstract
The patch clamp method is a widely applied electrophysiological technique used to understand ion channel activity and cellular excitation. The formation of a high resistance giga-ohm seal is required to obtain high-quality recordings but can be challenging due to variables including operator experience and cell preparation. Therefore, the identification of methods to promote the formation and longevity of giga-ohm seals may be beneficial. In this report, we describe our observation that the application of reducing agents (DTT and TCEP) to the external bath solution during whole-cell patch clamp recordings of heterologous cells (HEK and LM) and cultured primary cells (DRG neurons) enhanced the success of giga-ohm seal formation. Reducing agents also maintained the integrity of the seal for longer periods of time at strong hyperpolarizing voltages, whereas an oxidizing agent (H2O2) appeared to have the opposite effect. In summary, we report a useful tool to improve the quality of patch clamp recordings that may be helpful in certain experimental contexts.
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Affiliation(s)
- Damayantee Das
- Dept. of Pharmacology, Alberta Diabetes Institute, University of Alberta, Edmonton, Canada
| | - Anson Wong
- Dept. of Pharmacology, Alberta Diabetes Institute, University of Alberta, Edmonton, Canada
| | - Timothy N. Friedman
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Canada
| | - Bradley J Kerr
- Dept. of Pharmacology, Alberta Diabetes Institute, University of Alberta, Edmonton, Canada
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Canada
- Department of Anesthesiology and Pain Medicine, University of Alberta, Edmonton, Canada
| | - Harley T. Kurata
- Dept. of Pharmacology, Alberta Diabetes Institute, University of Alberta, Edmonton, Canada
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Canada
| | - Shawn M. Lamothe
- Dept. of Pharmacology, Alberta Diabetes Institute, University of Alberta, Edmonton, Canada
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Bertagna F, Ahmad S, Lewis R, Silva SRP, McFadden J, Huang CLH, Matthews HR, Jeevaratnam K. Loose patch clamp membrane current measurements in cornus ammonis 1 neurons in murine hippocampal slices. Ann N Y Acad Sci 2024; 1535:62-75. [PMID: 38602714 DOI: 10.1111/nyas.15123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 12/19/2023] [Accepted: 02/16/2024] [Indexed: 04/12/2024]
Abstract
Hippocampal pyramidal neuronal activity has been previously studied using conventional patch clamp in isolated cells and brain slices. We here introduce the loose patch clamping study of voltage-activated currents from in situ pyramidal neurons in murine cornus ammonis 1 hippocampal coronal slices. Depolarizing pulses of 15-ms duration elicited early transient inward, followed by transient and prolonged outward currents in the readily identifiable junctional region between the stratum pyramidalis (SP) and oriens (SO) containing pyramidal cell somas and initial segments. These resembled pyramidal cell currents previously recorded using conventional patch clamp. Shortening the depolarizing pulses to >1-2 ms continued to evoke transient currents; hyperpolarizing pulses to varying voltages evoked decays whose time constants could be shortened to <1 ms, clarifying the speed of clamping in this experimental system. The inward and outward currents had distinct pharmacological characteristics and voltage-dependent inactivation and recovery from inactivation. Comparative recordings from the SP, known to contain pyramidal cell somas, demonstrated similar current properties. Recordings from the SO and stratum radiatum demonstrated smaller inward and outward current magnitudes and reduced transient outward currents, consistent with previous conventional patch clamp results from their different interneuron types. The loose patch clamp method is thus useful for in situ studies of neurons in hippocampal brain slices.
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Affiliation(s)
- Federico Bertagna
- Leverhulme Quantum Biology Doctoral Training Centre, University of Surrey, Guildford, UK
- School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK
| | - Shiraz Ahmad
- School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK
| | - Rebecca Lewis
- Leverhulme Quantum Biology Doctoral Training Centre, University of Surrey, Guildford, UK
- School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK
| | - S Ravi P Silva
- Leverhulme Quantum Biology Doctoral Training Centre, University of Surrey, Guildford, UK
- Advanced Technology Institute, University of Surrey, Guildford, UK
| | - Johnjoe McFadden
- Leverhulme Quantum Biology Doctoral Training Centre, University of Surrey, Guildford, UK
- School of Biosciences and Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK
| | - Christopher L-H Huang
- School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK
- Physiological Laboratory, University of Cambridge, Cambridge, UK
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Hugh R Matthews
- Physiological Laboratory, University of Cambridge, Cambridge, UK
| | - Kamalan Jeevaratnam
- Leverhulme Quantum Biology Doctoral Training Centre, University of Surrey, Guildford, UK
- School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK
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Bertagna F, Ahmad S, Lewis R, Silva SRP, McFadden J, Huang CLH, Matthews HR, Jeevaratnam K. Loose-patch clamp analysis applied to voltage-gated ionic currents following pharmacological ryanodine receptor modulation in murine hippocampal cornu ammonis-1 pyramidal neurons. Front Physiol 2024; 15:1359560. [PMID: 38720787 PMCID: PMC11076846 DOI: 10.3389/fphys.2024.1359560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Accepted: 04/04/2024] [Indexed: 05/12/2024] Open
Abstract
Introduction The loose-patch clamp technique was first developed and used in native amphibian skeletal muscle (SkM), offering useful features complementing conventional sharp micro-electrode, gap, or conventional patch voltage clamping. It demonstrated the feedback effects of pharmacological modification of ryanodine receptor (RyR)-mediated Ca2+ release on the Na+ channel (Nav1.4) currents, initiating excitation-contraction coupling in native murine SkM. The effects of the further RyR and Ca2+-ATPase (SERCA) antagonists, dantrolene and cyclopiazonic acid (CPA), additionally implicated background tubular-sarcoplasmic Ca2+ domains in these actions. Materials and methods We extend the loose-patch clamp approach to ion current measurements in murine hippocampal brain slice cornu ammonis-1 (CA1) pyramidal neurons. We explored the effects on Na+ currents of pharmacologically manipulating RyR and SERCA-mediated intracellular store Ca2+ release and reuptake. We adopted protocols previously applied to native skeletal muscle. These demonstrated Ca2+-mediated feedback effects on the Na+ channel function. Results Experiments applying depolarizing 15 ms duration loose-patch clamp steps to test voltages ranging from -40 to 120 mV positive to the resting membrane potential demonstrated that 0.5 mM caffeine decreased inward current amplitudes, agreeing with the previous SkM findings. It also decreased transient but not prolonged outward current amplitudes. However, 2 mM caffeine affected neither inward nor transient outward but increased prolonged outward currents, in contrast to its increasing inward currents in SkM. Furthermore, similarly and in contrast to previous SkM findings, both dantrolene (10 μM) and CPA (1 μM) pre-administration left both inward and outward currents unchanged. Nevertheless, dantrolene pretreatment still abrogated the effects of subsequent 0.5- and 2-mM caffeine challenges on both inward and outward currents. Finally, CPA abrogated the effects of 0.5 mM caffeine on both inward and outward currents, but with 2 mM caffeine, inward and transient outward currents were unchanged, but sustained outward currents increased. Conclusion We, thus, extend loose-patch clamping to establish pharmacological properties of murine CA1 pyramidal neurons and their similarities and contrasts with SkM. Here, evoked though not background Ca2+-store release influenced Nav and Kv excitation, consistent with smaller contributions of background store Ca2+ release to resting [Ca2+]. This potential non-canonical mechanism could modulate neuronal membrane excitability or cellular firing rates.
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Affiliation(s)
- Federico Bertagna
- Leverhulme Quantum Biology Doctoral Training Centre, University of Surrey, Guildford, United Kingdom
- School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
| | - Shiraz Ahmad
- School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
| | - Rebecca Lewis
- Leverhulme Quantum Biology Doctoral Training Centre, University of Surrey, Guildford, United Kingdom
- School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
| | - S. Ravi P. Silva
- Leverhulme Quantum Biology Doctoral Training Centre, University of Surrey, Guildford, United Kingdom
- Advanced Technology Institute, University of Surrey, Guildford, United Kingdom
| | - Johnjoe McFadden
- Leverhulme Quantum Biology Doctoral Training Centre, University of Surrey, Guildford, United Kingdom
- School of Biosciences and Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
| | - Christopher L.-H. Huang
- School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
- Physiological Laboratory, University of Cambridge, Cambridge, United Kingdom
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Hugh R. Matthews
- Physiological Laboratory, University of Cambridge, Cambridge, United Kingdom
| | - Kamalan Jeevaratnam
- Leverhulme Quantum Biology Doctoral Training Centre, University of Surrey, Guildford, United Kingdom
- School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
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Huang B, Yan L, Li Y, Liu W, Liu M, Xiao Z, Huang J. Urethane Improves the Response of Auditory Neurons to Tone. Front Cell Neurosci 2022; 16:855968. [PMID: 35783092 PMCID: PMC9240349 DOI: 10.3389/fncel.2022.855968] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2022] [Accepted: 05/12/2022] [Indexed: 11/21/2022] Open
Abstract
Urethane has little effect on nervous system and is often used in neuroscience studies. However, the effect of urethane in neurons is not thoroughly clear. In this study, we investigated changes in neuron responses to tones in inferior colliculus during urethane anesthesia. As urethane was metabolized, the best and characteristic frequencies did not obviously change, but the minimal threshold (MT) remained relatively stable or was elevated. The frequency tuning bandwidth at 60 dB SPL (BW60dBSPL) remained unchanged or decreased, and the average evoked spike of effective frequencies at 60 dB SPL (ES60dBSPL) gradually decreased. Although the average evoked spike of effective frequencies at a tone intensity of 20 dB SPL above MT (ES20dBSPLaboveMT) decreased, the frequency tuning bandwidth at a tone intensity of 20 dB SPL above MT (BW20dBSPLaboveMT) did not change. In addition, the changes in MT, ES60dBSPL, BW60dBSPL, and ES20dBSPLaboveMT increased with the MT in pre-anesthesia awake state (MTpre−anesthesiaawake). In some neurons, the MT was lower, BW60dBSPL was broader, and ES60dBSPL and ES20dBSPLaboveMT were higher in urethane anesthesia state than in pre-anesthesia awake state. During anesthesia, the inhibitory effect of urethane reduced the ES20dBSPLaboveMT, but did not change the MT, characteristic frequency, or BW20dBSPLaboveMT. In the recording session with the strongest neuron response, the first spike latency did not decrease, and the spontaneous spike did not increase. Therefore, we conclude that urethane can reduce/not change the MT, increase the evoked spike, or broaden/not change the frequency tuning range, and eventually improve the response of auditory neurons to tone with or without “pushing down” the tonal receptive field in thresholding model. The improved effect increases with the MTpre−anesthesiaawake of neurons. The changes induced by the inhibitory and improved effects of urethane abide by similar regularities, but the change directions are contrary. The improvement mechanism may be likely due to the increase in the ratio of excitatory/inhibitory postsynaptic inputs to neurons.
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Affiliation(s)
- Bowan Huang
- Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
- Department of Anesthesiology, Shenzhen Traditional Chinese Medicine Hospital, The Fourth Clinical Medical College of Guangzhou University of Chinese Medicine, Shenzhen, China
| | - Linqing Yan
- Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Yan Li
- Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Wenhui Liu
- The Seventh Affiliated Hospital, Southern Medical University, Foshan, China
| | - Manhua Liu
- The Seventh Affiliated Hospital, Southern Medical University, Foshan, China
| | - Zhongju Xiao
- Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
- The Seventh Affiliated Hospital, Southern Medical University, Foshan, China
- *Correspondence: Zhongju Xiao
| | - Jinping Huang
- The Seventh Affiliated Hospital, Southern Medical University, Foshan, China
- Jinping Huang
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