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Sensors (Basel, Switzerland) Feb 2021Brain functions are fundamental for the survival of organisms, and they are supported by neural circuits consisting of a variety of neurons. To investigate the function... (Review)
Review
Brain functions are fundamental for the survival of organisms, and they are supported by neural circuits consisting of a variety of neurons. To investigate the function of neurons at the single-cell level, researchers often use whole-cell patch-clamp recording techniques. These techniques enable us to record membrane potentials (including action potentials) of individual neurons of not only anesthetized but also actively behaving animals. This whole-cell recording method enables us to reveal how neuronal activities support brain function at the single-cell level. In this review, we introduce previous studies using in vivo patch-clamp recording techniques and recent findings primarily regarding neuronal activities in the hippocampus for behavioral function. We further discuss how we can bridge the gap between electrophysiology and biochemistry.
Topics: Action Potentials; Animals; Hippocampus; Membrane Potentials; Neurons; Patch-Clamp Techniques
PubMed: 33669656
DOI: 10.3390/s21041448 -
Neuroscience Bulletin Aug 2012Patch-clamp recording requires direct accessibility of the cell membrane to patch pipettes and allows the investigation of ion channel properties and functions in... (Review)
Review
Patch-clamp recording requires direct accessibility of the cell membrane to patch pipettes and allows the investigation of ion channel properties and functions in specific cellular compartments. The cell body and relatively thick dendrites are the most accessible compartments of a neuron, due to their large diameters and therefore great membrane surface areas. However, axons are normally inaccessible to patch pipettes because of their thin structure; thus studies of axon physiology have long been hampered by the lack of axon recording methods. Recently, a new method of patch-clamp recording has been developed, enabling direct and tight-seal recording from cortical axons. These recordings are performed at the enlarged structure (axonal bleb) formed at the cut end of an axon after slicing procedures. This method has facilitated studies of the mechanisms underlying the generation and propagation of the main output signal, the action potential, and led to the finding that cortical neurons communicate not only in action potential-mediated digital mode but also in membrane potential-dependent analog mode.
Topics: Action Potentials; Animals; Axons; Dendrites; Humans; Membrane Potentials; Neurons; Patch-Clamp Techniques
PubMed: 22833034
DOI: 10.1007/s12264-012-1247-1 -
Biomedical Journal Oct 2022The brain is the most unexplored part of our body. The lack of sufficient tools has hindered our understanding of the brain and the associated diseases. The study of... (Review)
Review
The brain is the most unexplored part of our body. The lack of sufficient tools has hindered our understanding of the brain and the associated diseases. The study of neurons and the neuronal network will help elucidate how the brain functions and related disorders. Over the last few decades, an increasing number of techniques have been reported to study neurons and neuronal communication in vitro, ex vivo, and in vivo. These methods have pushed the boundaries of neuroscience and elucidated more information than ever before; however, much more requires to be done to understand the brain in its entirety. In this review article, I discuss the principles and the advantages and disadvantages of the classical electrode-based recording techniques and the optical imaging-based methods, which have aided neuroscientists in understanding neuronal communication.
Topics: Humans; Membrane Potentials; Neurons; Brain; Fluorescent Dyes
PubMed: 35667642
DOI: 10.1016/j.bj.2022.05.007 -
Archives of Insect Biochemistry and... Jun 2022The functioning of voltage-dependent K channels (Kv) may correlate with the physiological state of brain in organisms, including the sleep in Drosophila. Apparently, all... (Review)
Review
The functioning of voltage-dependent K channels (Kv) may correlate with the physiological state of brain in organisms, including the sleep in Drosophila. Apparently, all major types of K currents are expressed in CNS of this model organism. These are the Shab-Kv2, Shaker-Kv1, Shal-Kv4, and Shaw-Kv3 α subunits and can be deciphered by patch-clamp technique. Although it is plausible that some of these channels may play a prevailing role in sleep or wakefulness, several of recent data are not conclusive. It needs to be defined that indeed the frequency of action potentials in large ventral lateral pacemaker neurons is either higher or lower during the morning or night because of an increased Kv3 and Kv4 currents, respectively. The outcomes of dynamic-clamp approach in combination with electrophysiology in insects are unreliable in contrast to those in mammalian neurons. Since the addition of virtual Kv conductance during any Zeitgeber time should not significantly alter the resting membrane potential. This review explains the Drosophila sleep behavior based on neural activity with respect to K current-driven action potential rate.
Topics: Animals; Drosophila; Mammals; Membrane Potentials; Neurons; Patch-Clamp Techniques; Sleep
PubMed: 35313039
DOI: 10.1002/arch.21884 -
Sensors (Basel, Switzerland) Oct 2015Beta cells in the pancreatic islets of Langerhans are precise biological sensors for glucose and play a central role in balancing the organism between catabolic and... (Review)
Review
Beta cells in the pancreatic islets of Langerhans are precise biological sensors for glucose and play a central role in balancing the organism between catabolic and anabolic needs. A hallmark of the beta cell response to glucose are oscillatory changes of membrane potential that are tightly coupled with oscillatory changes in intracellular calcium concentration which, in turn, elicit oscillations of insulin secretion. Both membrane potential and calcium changes spread from one beta cell to the other in a wave-like manner. In order to assess the properties of the abovementioned responses to physiological and pathological stimuli, the main challenge remains how to effectively measure membrane potential and calcium changes at the same time with high spatial and temporal resolution, and also in as many cells as possible. To date, the most wide-spread approach has employed the electrophysiological patch-clamp method to monitor membrane potential changes. Inherently, this technique has many advantages, such as a direct contact with the cell and a high temporal resolution. However, it allows one to assess information from a single cell only. In some instances, this technique has been used in conjunction with CCD camera-based imaging, offering the opportunity to simultaneously monitor membrane potential and calcium changes, but not in the same cells and not with a reliable cellular or subcellular spatial resolution. Recently, a novel family of highly-sensitive membrane potential reporter dyes in combination with high temporal and spatial confocal calcium imaging allows for simultaneously detecting membrane potential and calcium changes in many cells at a time. Since the signals yielded from both types of reporter dyes are inherently noisy, we have developed complex methods of data denoising that permit for visualization and pixel-wise analysis of signals. Combining the experimental approach of high-resolution imaging with the advanced analysis of noisy data enables novel physiological insights and reassessment of current concepts in unprecedented detail.
Topics: Animals; Calcium; Islets of Langerhans; Membrane Potentials; Mice; Models, Biological; Optical Imaging
PubMed: 26516866
DOI: 10.3390/s151127393 -
Trends in Microbiology Apr 2020All cellular membranes have the functionality of generating and maintaining the gradients of electrical and electrochemical potentials. Such potentials were generally... (Review)
Review
All cellular membranes have the functionality of generating and maintaining the gradients of electrical and electrochemical potentials. Such potentials were generally thought to be an essential but homeostatic contributor to complex bacterial behaviors. Recent studies have revised this view, and we now know that bacterial membrane potential is dynamic and plays signaling roles in cell-cell interaction, adaptation to antibiotics, and sensation of cellular conditions and environments. These discoveries argue that bacterial membrane potential dynamics deserve more attention. Here, we review the recent studies revealing the signaling roles of bacterial membrane potential dynamics. We also introduce basic biophysical theories of the membrane potential to the microbiology community and discuss the needs to revise these theories for applications in bacterial electrophysiology.
Topics: Anti-Bacterial Agents; Bacteria; Biofilms; Biophysics; Drug Resistance, Bacterial; Electrophysiology; Eukaryota; Membrane Potentials
PubMed: 31952908
DOI: 10.1016/j.tim.2019.12.008 -
International Journal of Molecular... Nov 2022G protein-coupled receptors (GPCRs) are involved in a vast majority of signal transduction processes. Although they span the cell membrane, they have not been considered... (Review)
Review
G protein-coupled receptors (GPCRs) are involved in a vast majority of signal transduction processes. Although they span the cell membrane, they have not been considered to be regulated by the membrane potential. Numerous studies over the last two decades have demonstrated that several GPCRs, including muscarinic, adrenergic, dopaminergic, and glutamatergic receptors, are voltage regulated. Following these observations, an effort was made to elucidate the molecular basis for this regulatory effect. In this review, we will describe the advances in understanding the voltage dependence of GPCRs, the suggested molecular mechanisms that underlie this phenomenon, and the possible physiological roles that it may play.
Topics: Membrane Potentials; Signal Transduction; Receptors, G-Protein-Coupled; Cell Membrane
PubMed: 36430466
DOI: 10.3390/ijms232213988 -
Methods in Enzymology 2021Membrane potential is a fundamental biophysical parameter common to all of cellular life. Traditional methods to measure membrane potential rely on electrodes, which are...
Membrane potential is a fundamental biophysical parameter common to all of cellular life. Traditional methods to measure membrane potential rely on electrodes, which are invasive and low-throughput. Optical methods to measure membrane potential are attractive because they have the potential to be less invasive and higher throughput than classic electrode based techniques. However, most optical measurements rely on changes in fluorescence intensity to detect changes in membrane potential. In this chapter, we discuss the use of fluorescence lifetime imaging microscopy (FLIM) and voltage-sensitive fluorophores (VoltageFluors, or VF dyes) to estimate the millivolt value of membrane potentials in living cells. We discuss theory, application, protocols, and shortcomings of this approach.
Topics: Fluorescent Dyes; Membrane Potentials; Microscopy, Fluorescence; Optical Imaging
PubMed: 34099175
DOI: 10.1016/bs.mie.2021.02.009 -
Physiological Reports Jan 2023The purpose of this study was to determine how sensory neurons respond to high-frequency membrane potential alternation between depolarization and hyperpolarization....
The purpose of this study was to determine how sensory neurons respond to high-frequency membrane potential alternation between depolarization and hyperpolarization. Membrane currents were recorded from dissociated dorsal root ganglion (DRG) neurons of adult rats using the whole cell patch clamp technique in voltage clamp mode. Stepwise depolarization of the membrane was applied first to determine the threshold membrane potential for inducing an action potential (AP) current. Then, membrane potential alternation between depolarization (to +20 mV) and hyperpolarization (to -110 mV) was applied to the neuron for 10 s at different frequencies (10 Hz to 1 kHz). The tested DRG neurons had APs of either a long duration (>10 ms) or a short duration (<10 ms). Membrane potential alternation at ≥500 Hz completely disrupted the AP generation, disabled the ion channel gating function, and produced membrane current alternating symmetrically across zero. Replacing extracellular sodium with potassium increased the amplitude of the membrane current response and caused the membrane current to be larger during hyperpolarization than during depolarization. These results support the hypothesis that high-frequency biphasic stimulation blocks axonal conduction by driving the potassium channel open constantly. Understanding neural membrane response to high-frequency membrane potential alternation is important to reveal the possible mechanisms underlying axonal conduction block induced by high-frequency biphasic stimulation.
Topics: Rats; Animals; Membrane Potentials; Ganglia, Spinal; Neurons; Action Potentials; Neurons, Afferent
PubMed: 36695759
DOI: 10.14814/phy2.15582 -
International Journal of Molecular... Sep 2015Membrane potentials display the cellular status of non-excitable cells and mediate communication between excitable cells via action potentials. The use of genetically... (Review)
Review
Membrane potentials display the cellular status of non-excitable cells and mediate communication between excitable cells via action potentials. The use of genetically encoded biosensors employing fluorescent proteins allows a non-invasive biocompatible way to read out the membrane potential in cardiac myocytes and other cells of the circulation system. Although the approaches to design such biosensors date back to the time when the first fluorescent-protein based Förster Resonance Energy Transfer (FRET) sensors were constructed, it took 15 years before reliable sensors became readily available. Here, we review different developments of genetically encoded membrane potential sensors. Furthermore, it is shown how such sensors can be used in pharmacological screening applications as well as in circulation related basic biomedical research. Potentials and limitations will be discussed and perspectives of possible future developments will be provided.
Topics: Action Potentials; Animals; Animals, Genetically Modified; Biosensing Techniques; Cardiovascular System; Fluorescence Resonance Energy Transfer; Gene Expression; Genes, Reporter; Humans; Membrane Potentials; Myocytes, Cardiac; Recombinant Fusion Proteins; Research; Voltage-Sensitive Dye Imaging
PubMed: 26370981
DOI: 10.3390/ijms160921626