Role of Electrotonic Current in Excitable Cells

2018 ◽  
pp. 87-114
Author(s):  
Emilio Macchi ◽  
Ezio Musso ◽  
Stefano Rossi
Keyword(s):  
Excitable Cells

scholarly journals Calnexin revealed as an ether-a-go-go chaperone by getting mutant worms up and going

2018 ◽  
Vol 150 (8) ◽  
pp. 1059-1061
Author(s):  
Jonathan T. Pierce
Keyword(s):  
Ion Channels ◽  
Dynamic Control ◽  
Cell Types ◽  
K Channel ◽  
Membrane Domains ◽  
Excitable Cells ◽  
Patch Clamp Recording ◽  
Cell Excitability ◽  
Distinct Membrane

The role of ion channels in cell excitability was first revealed in a series of voltage clamp experiments by Hodgkin and Huxley in the 1950s. However, it was not until the 1970s that patch-clamp recording ushered in a revolution that allowed physiologists to witness how ion channels flicker open and closed at angstrom scale and with microsecond resolution. The unexpectedly tight seal made by the patch pipette in the whole-cell configuration later allowed molecular biologists to suck up the insides of identified cells to unveil their unique molecular contents. By refining these techniques, researchers have scrutinized the surface and contents of excitable cells in detail over the past few decades. However, these powerful approaches do not discern which molecules are responsible for the dynamic control of the genesis, abundance, and subcellular localization of ion channels. In this dark territory, teams of unknown and poorly understood molecules guide specific ion channels through translation, folding, and modification, and then they shuttle them toward and away from distinct membrane domains via different subcellular routes. A central challenge in understanding these processes is the likelihood that these diverse regulatory molecules may be specific to ion channel subtypes, cell types, and circumstance. In work described in this issue, Bai et al. (2018. J. Gen. Physiol. https://doi.org/10.1085/jgp.201812025) begin to shed light on the biogenesis of UNC-103, a K+ channel found in Caenorhabditis elegans.

Role of Cyclic Nucleotides in Excitable Cells

1980 ◽  
Vol 42 (1) ◽  
pp. 629-641 ◽  
Author(s):  
I Kupfermann
Keyword(s):  
Cyclic Nucleotides ◽  
Excitable Cells

scholarly journals Silencing of Plasma Membrane Ca2+-ATPase Isoforms 2 and 3 Impairs Energy Metabolism in Differentiating PC12 Cells

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Tomasz Boczek ◽  
Malwina Lisek ◽  
Bozena Ferenc ◽  
Antoni Kowalski ◽  
Magdalena Wiktorska ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Pc12 Cells ◽  
Molecular Mechanisms ◽  
Atp Synthesis ◽  
Mitochondrial Activity ◽  
Excitable Cells ◽  
Close Link ◽  
Atp Level ◽  
Atp Generation

A close link between Ca2+, ATP level, and neurogenesis is apparent; however, the molecular mechanisms of this relationship have not been completely elucidated. Transient elevations of cytosolic Ca2+may boost ATP synthesis, but ATP is also consumed by ion pumps to maintain a low Ca2+in cytosol. In differentiation process plasma membrane Ca2+ATPase (PMCA) is considered as one of the major players for Ca2+homeostasis. From four PMCA isoforms, the fastest PMCA2 and PMCA3 are expressed predominantly in excitable cells. In the present study we assessed whether PMCA isoform composition may affect energy balance in differentiating PC12 cells. We found that PMCA2-downregulated cells showed higher basal O2consumption, lower NAD(P)H level, and increased activity of ETC. These changes associated with higher[Ca2+]cresulted in elevated ATP level. Since PMCA2-reduced cells demonstrated greatest sensitivity to ETC inhibition, we suppose that the main source of energy for PMCA isoforms 1, 3, and 4 was oxidative phosphorylation. Contrary, cells with unchanged PMCA2 expression exhibited prevalence of glycolysis in ATP generation. Our results with PMCA2- or PMCA3-downregulated lines provide an evidence of a novel role of PMCA isoforms in regulation of bioenergetic pathways, and mitochondrial activity and maintenance of ATP level during PC12 cells differentiation.

scholarly journals Inositol 1,4,5-Trisphosphate Directs Ca2+Flow between Mitochondria and the Endoplasmic/Sarcoplasmic Reticulum: A Role in Regulating Cardiac Autonomic Ca2+ Spiking

2000 ◽  
Vol 11 (5) ◽  
pp. 1845-1858 ◽  
Author(s):  
Marisa Jaconi ◽  
Claire Bony ◽  
Stephen M. Richards ◽  
André Terzic ◽  
Serge Arnaudeau ◽  
...  
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Dominant Negative ◽  
Neonatal Rat ◽  
Excitable Cells ◽  
Rat Cardiomyocytes ◽  
Cell Functions ◽  
Inositol 1,4,5 Trisphosphate ◽  
Cellular Ca ◽  
Cardiac Autonomic Activity

The signaling role of the Ca2+ releaser inositol 1,4,5-trisphosphate (IP3) has been associated with diverse cell functions. Yet, the physiological significance of IP3 in tissues that feature a ryanodine-sensitive sarcoplasmic reticulum has remained elusive. IP3 generated by photolysis of caged IP3 or by purinergic activation of phospholipase Cγ slowed down or abolished autonomic Ca2+ spiking in neonatal rat cardiomyocytes. Microinjection of heparin, blocking dominant-negative fusion protein, or anti-phospholipase Cγ antibody prevented the IP3-mediated purinergic effect. IP3 triggered a ryanodine- and caffeine-insensitive Ca2+ release restricted to the perinuclear region. In cells loaded with Rhod2 or expressing a mitochondria-targeted cameleon and TMRM to monitor mitochondrial Ca2+ and potential, IP3 induced transient Ca2+ loading and depolarization of the organelles. These mitochondrial changes were associated with Ca2+ depletion of the sarcoplasmic reticulum and preceded the arrest of cellular Ca2+ spiking. Thus, IP3 acting within a restricted cellular region regulates the dynamic of calcium flow between mitochondria and the endoplasmic/sarcoplasmic reticulum. We have thus uncovered a novel role for IP3 in excitable cells, the regulation of cardiac autonomic activity.

scholarly journals TASK-1 (KCNK3) channels in the lung: from cell biology to clinical implications

2017 ◽  
Vol 50 (5) ◽  
pp. 1700754 ◽  
Author(s):  
Andrea Olschewski ◽  
Emma L. Veale ◽  
Bence M. Nagy ◽  
Chandran Nagaraj ◽  
Grazyna Kwapiszewska ◽  
...  
Keyword(s):  
Pulmonary Circulation ◽  
Cell Biology ◽  
Unsaturated Fatty Acids ◽  
Excitable Cells ◽  
Intracellular Signalling Pathways ◽  
Current State ◽  
Health And Disease ◽  
Pulmonary Arterial ◽  
Pore Domain

TWIK-related acid-sensitive potassium channel 1 (TASK-1 encoded by KCNK3) belongs to the family of two-pore domain potassium channels. This gene subfamily is constitutively active at physiological resting membrane potentials in excitable cells, including smooth muscle cells, and has been particularly linked to the human pulmonary circulation. TASK-1 channels are sensitive to a wide array of physiological and pharmacological mediators that affect their activity such as unsaturated fatty acids, extracellular pH, hypoxia, anaesthetics and intracellular signalling pathways. Recent studies show that modulation of TASK-1 channels, either directly or indirectly by targeting their regulatory mechanisms, has the potential to control pulmonary arterial tone in humans. Furthermore, mutations in KCNK3 have been identified as a rare cause of both familial and idiopathic pulmonary arterial hypertension. This review summarises our current state of knowledge of the functional role of TASK-1 channels in the pulmonary circulation in health and disease, with special emphasis on current advancements in the field.

scholarly journals Role of STIM1 protein in the regulation of store-operated channels in non-excitable cells

2009 ◽  
Vol 3 (3) ◽  
pp. 329-329
Author(s):  
I. A. Pozdnjakov ◽  
V. A. Vigont ◽  
O. A. Zimina ◽  
A. Yu. Skopin ◽  
L. N. Glushankova ◽  
...  
Keyword(s):  
Excitable Cells

scholarly journals Modeling the role of endoplasmic reticulum-mitochondria microdomains in calcium dynamics

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Arash Moshkforoush ◽  
Baarbod Ashenagar ◽  
Nikolaos M. Tsoukias ◽  
B. Rita Alevriadou
Keyword(s):  
Endoplasmic Reticulum ◽  
Vascular Endothelial Cells ◽  
Cell Model ◽  
Vascular Endothelial ◽  
Calcium Dynamics ◽  
Mitochondrial Membranes ◽  
Excitable Cells ◽  
Closed Cell ◽  
Stimulation Of

AbstractUpon inositol trisphosphate (IP3) stimulation of non-excitable cells, including vascular endothelial cells, calcium (Ca2+) shuttling between the endoplasmic reticulum (ER) and mitochondria, facilitated by complexes called Mitochondria-Associated ER Membranes (MAMs), is known to play an important role in the occurrence of cytosolic Ca2+ concentration ([Ca2+]Cyt) oscillations. A mathematical compartmental closed-cell model of Ca2+ dynamics was developed that accounts for ER-mitochondria Ca2+ microdomains as the µd compartment (besides the cytosol, ER and mitochondria), Ca2+ influx to/efflux from each compartment and Ca2+ buffering. Varying the distribution of functional receptors in MAMs vs. the rest of ER/mitochondrial membranes, a parameter called the channel connectivity coefficient (to the µd), allowed for generation of [Ca2+]Cytoscillations driven by distinct mechanisms at various levels of IP3 stimulation. Oscillations could be initiated by the transient opening of IP3 receptors facing either the cytosol or the µd, and subsequent refilling of the respective compartment by Ca2+ efflux from the ER and/or the mitochondria. Only under conditions where the µd became the oscillation-driving compartment, silencing the Mitochondrial Ca2+ Uniporter led to oscillation inhibition. Thus, the model predicts that alternative mechanisms can yield [Ca2+]Cyt oscillations in non-excitable cells, and, under certain conditions, the ER-mitochondria µd can play a regulatory role.

The role of sodium-calcium exchange in excitable cells

1988 ◽  
Vol 16 (4) ◽  
pp. 529-532 ◽  
Author(s):  
GREGORY J. KACZOROWSKI ◽  
ROBERT S. SLAUGHTER ◽  
MARIA L. GARCIA ◽  
V. FRANK KING
Keyword(s):  
Excitable Cells ◽  
Sodium Calcium ◽  
Calcium Exchange ◽  
Sodium Calcium Exchange

Store-Operated Calcium Entry Channels

2017 ◽  
pp. 53-72
Author(s):  
Diptiman D. Bose
Keyword(s):  
Cardiac Function ◽  
Immune Cells ◽  
Cellular Functions ◽  
Excitable Cells ◽  
Extracellular Milieu ◽  
Store Operated Calcium Entry ◽  
Endoplasmic Reticulum Protein ◽  
Cardiac Disorders ◽  
Ca2 Channels

Store-operated Ca2+ entry (SOCE) channels mediate Ca2+ influx from the extracellular milieu into the cytosol to regulate a myriad of cellular functions. The Ca2+-release activated Ca2+ current has been well characterized in non-excitable cells such as immune cells. However, the role of SOCE proteins in cardiomyocytes and cardiac function has only been recently investigated. The localized endoplasmic reticulum protein, stromal interaction molecule (STIM) and plasma membrane Ca2+ channels, ORAI form the minimal functional unit of SOCE. The documentation of STIM and Orai expression in cardiomyocytes has raised questions regarding their role in cardiac function. Recent evidence supports the central role of STIM and Orai in gene transcription and, subsequent phenotypic changes associated with cardiac remodeling and hypertrophy. The purpose of this chapter is to provide an overview of our current understanding of SOCE proteins and, to explore their contributions to cardiovascular function and role in cardiac disorders.

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