Involvement of the Ryanodine Receptor in Morphologic Modification of Hermissenda Type B Photoreceptors After In Vitro Conditioning

2004 ◽  
Vol 91 (2) ◽  
pp. 728-735 ◽  
Author(s):  
Ryo Kawai ◽  
Tetsuro Horikoshi ◽  
Manabu Sakakibara
Keyword(s):  
Ryanodine Receptor ◽  
Hair Cells ◽  
Ryanodine Receptors ◽  
Terminal Branch ◽  
Type B ◽  
Axon Terminals ◽  
Calcium Chelation ◽  
Intracellular Ca ◽  
Receptor Blockers

We examined whether Ca2+ induced Ca2+ release through ryanodine receptors is involved in the conditioning of specific morphologic changes at the axon terminals of type B photoreceptors in the isolated circumesophageal ganglion of Hermissenda. Calcium chelation by bis(2-aminophenoxy) ethane- N,N,N′, N′-tetraacetic acid prevented the conformational change at the terminals after five paired presentations of light and vibration, which produce terminal branch contraction of B photoreceptors. Two ryanodine receptor blockers, dantrolene and micromolar concentrations of ryanodine, depressed the increase in excitability due to in vitro conditioning and the increase in intracellular Ca2+ in response to membrane depolarization. Although the ability to increase intracellular Ca2+ was depressed, synaptic transmission was preserved in the normal state from hair cells under dantrolene and ryanodine incubation. Ryanodine receptor blockers also prevented contraction at the B photoreceptor axon terminals. These results suggest that the ryanodine receptor has a crucial role in inducing the in vitro conditioning specific changes both physiologically and morphologically, including “focusing” at the B photoreceptor axon terminal.

scholarly journals The ryanodine receptor/calcium channel genes are widely and differentially expressed in murine brain and peripheral tissues.

1995 ◽  
Vol 128 (5) ◽  
pp. 893-904 ◽  
Author(s):  
G Giannini ◽  
A Conti ◽  
S Mammarella ◽  
M Scrobogna ◽  
V Sorrentino
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Intracellular Calcium ◽  
Ryanodine Receptor ◽  
Calcium Release ◽  
Ryanodine Receptors ◽  
Calcium Release Channels ◽  
Peripheral Tissues ◽  
The Central Nervous System

Ryanodine receptors (RyRs) are intracellular calcium release channels that participate in controlling cytosolic calcium levels. At variance with the probably ubiquitous inositol 1,4,5-trisphosphate-operated calcium channels (1,4,5-trisphosphate receptors), RyRs have been mainly regarded as the calcium release channels controlling skeletal and cardiac muscle contraction. Increasing evidence has recently suggested that RyRs may be more widely expressed, but this has never been extensively examined. Therefore, we cloned three cDNAs corresponding to murine RyR homologues to carry a comprehensive analysis of their expression in murine tissues. Here, we report that the three genes are expressed in almost all tissues analyzed, where tissue-specific patterns of expression were observed. In the uterus and vas deferens, expression of RyR3 was localized to the smooth muscle component of these organs. In the testis, expression of RyR1 and RyR3 was detected in germ cells. RyR mRNAs were also detected in in vitro-cultured cell lines. RyR1, RyR2, and RyR3 mRNA were detected in the cerebrum and in the cerebellum. In situ analysis revealed a cell type-specific pattern of expression in the different regions of the central nervous system. The differential expression of the three ryanodine receptor genes in the central nervous system was also confirmed using specific antibodies against the respective proteins. This widespread pattern of expression suggests that RyRs may participate in the regulation of intracellular calcium homeostasis in a range of cells wider than previously recognized.

scholarly journals Differential Intracellular Distributions of Inositol Trisphosphate and Ryanodine Receptors Within and Among Hematopoietic Cells

2005 ◽  
Vol 53 (7) ◽  
pp. 913-916 ◽  
Author(s):  
Andrea J. Clark ◽  
Howard R. Petty
Keyword(s):  
Ryanodine Receptor ◽  
Immunofluorescence Microscopy ◽  
Ryanodine Receptors ◽  
Hematopoietic Cells ◽  
Cell Integrity ◽  
Fixation Methods ◽  
Inositol 1,4,5 Trisphosphate ◽  
Intracellular Ca ◽  
A Cell ◽  
Trisphosphate Receptor

To better understand the mechanism(s) of leukocyte Ca2+ signaling, we have studied the intracellular locations of two Ca2+-mobilizing receptors, the inositol 1,4,5-trisphosphate receptor and ryanodine receptor, by immunofluorescence microscopy. Our results show that localization differs not only between receptor classes within a cell, but among leukocyte types as well. We also illustrate the importance of preserving labile cellular filaments in maintaining cell integrity by fixation with the Safiejko-Mroczka and Bell protocol, because conventional fixation methods distort receptor patterns. We suggest that the observed differences influence intracellular Ca2+ signaling.

scholarly journals Caspofungin Modulates Ryanodine Receptor-Mediated Calcium Release in Human Cardiac Myocytes

2018 ◽  
Vol 62 (11) ◽  
Author(s):  
Christian Koch ◽  
Jennifer Jersch ◽  
Emmanuel Schneck ◽  
Fabian Edinger ◽  
Hagen Maxeiner ◽  
...  
Keyword(s):  
Cardiac Myocytes ◽  
Critically Ill ◽  
Ryanodine Receptor ◽  
Critically Ill Patients ◽  
Calcium Release ◽  
Ryanodine Receptors ◽  
Intracellular Ca ◽  
Hemodynamic Impairment ◽  
Dose Dependent Increase ◽  
Dose Dependent

ABSTRACT Recent studies showed that critically ill patients might be at risk for hemodynamic impairment during caspofungin (CAS) therapy. The aim of our present study was to examine the mechanisms behind CAS-induced cardiac alterations. We revealed a dose-dependent increase in intracellular Ca2+ concentration ([Ca2+]i) after CAS treatment. Ca2+ ions were found to be released from intracellular caffeine-sensitive stores, most probably via the activation of ryanodine receptors.

H2O2 activates ryanodine receptor but has little effect on recovery of releasable Ca2+ content after fatigue

2002 ◽  
Vol 93 (6) ◽  
pp. 1999-2008 ◽  
Author(s):  
Toshiharu Oba ◽  
Chieko Kurono ◽  
Ritsuko Nakajima ◽  
Tetsuo Takaishi ◽  
Kazuto Ishida ◽  
...  
Keyword(s):  
Redox Potential ◽  
Lipid Bilayers ◽  
Ryanodine Receptor ◽  
Ryanodine Receptors ◽  
Control Level ◽  
Recovery Process ◽  
Channel Activity ◽  
Channel Activation ◽  
Stimulation Of

We studied whether hydrogen peroxide (H2O2) at ≤10 μM activates the ryanodine receptor and decreases releasable Ca2+ content in the sarcoplasmic reticulum after fatigue. Exposure of rabbit or frog skeletal muscle ryanodine receptors to 10 μM H2O2 enhanced channel activity in lipid bilayers when the redox potential was defined at cis = −220 mV and trans = −180 mV. Channel activation by 10 μM H2O2 was also observed when cispotential was set at −220 mV without defining transpotential, but the effect was less. Reduction of trans redox potential from −180 to −220 mV did not alter channel activity. H2O2 at 500 μM failed to activate the channel when the redox potential was not controlled. Stimulation of the frog muscle fiber for 2 min (50 Hz, a duty cycle of 200 ms/s) decreased tetanus tension by ∼50%. After 1 min, tetanus recovered rapidly to ∼70% of control and thereafter slowly approached the control level. Amplitudes of caffeine- and 4-chloro- m-cresol-induced contractures were decreased after a 60-min rest. The decrease is not enhanced by exposure to 10 μM H2O2. These results suggest that H2O2 markedly activates the ryanodine receptor under the redox control in vitro, but externally applied H2O2 may not play an important role in the postfatigue recovery process.

Ryanodine Receptor Calcium Release Channels

2002 ◽  
Vol 82 (4) ◽  
pp. 893-922 ◽  
Author(s):  
Michael Fill ◽  
Julio A. Copello
Keyword(s):  
Ryanodine Receptor ◽  
Calcium Release ◽  
Striated Muscle ◽  
Ryanodine Receptors ◽  
Large Body ◽  
Future Directions ◽  
Calcium Release Channels ◽  
Coupling Process ◽  
Contraction Coupling ◽  
Intracellular Ca

The ryanodine receptors (RyRs) are a family of Ca2+ release channels found on intracellular Ca2+ storage/release organelles. The RyR channels are ubiquitously expressed in many types of cells and participate in a variety of important Ca2+ signaling phenomena (neurotransmission, secretion, etc.). In striated muscle, the RyR channels represent the primary pathway for Ca2+ release during the excitation-contraction coupling process. In general, the signals that activate the RyR channels are known (e.g., sarcolemmal Ca2+ influx or depolarization), but the specific mechanisms involved are still being debated. The signals that modulate and/or turn off the RyR channels remain ambiguous and the mechanisms involved unclear. Over the last decade, studies of RyR-mediated Ca2+ release have taken many forms and have steadily advanced our knowledge. This robust field, however, is not without controversial ideas and contradictory results. Controversies surrounding the complex Ca2+ regulation of single RyR channels receive particular attention here. In addition, a large body of information is synthesized into a focused perspective of single RyR channel function. The present status of the single RyR channel field and its likely future directions are also discussed.

scholarly journals “Ryanopathies” and RyR2 dysfunctions: can we further decipher them using in vitro human disease models?

2021 ◽  
Vol 12 (11) ◽  
Author(s):  
Yvonne Sleiman ◽  
Alain Lacampagne ◽  
Albano C. Meli
Keyword(s):  
Intracellular Calcium ◽  
Ryanodine Receptor ◽  
Calcium Release ◽  
Current Knowledge ◽  
Cell Types ◽  
Calcium Release Channel ◽  
Release Channel ◽  
Cellular Environment ◽  
Intracellular Ca

AbstractThe regulation of intracellular calcium (Ca2+) homeostasis is fundamental to maintain normal functions in many cell types. The ryanodine receptor (RyR), the largest intracellular calcium release channel located on the sarco/endoplasmic reticulum (SR/ER), plays a key role in the intracellular Ca2+ handling. Abnormal type 2 ryanodine receptor (RyR2) function, associated to mutations (ryanopathies) or pathological remodeling, has been reported, not only in cardiac diseases, but also in neuronal and pancreatic disorders. While animal models and in vitro studies provided valuable contributions to our knowledge on RyR2 dysfunctions, the human cell models derived from patients’ cells offer new hope for improving our understanding of human clinical diseases and enrich the development of great medical advances. We here discuss the current knowledge on RyR2 dysfunctions associated with mutations and post-translational remodeling. We then reviewed the novel human cellular technologies allowing the correlation of patient’s genome with their cellular environment and providing approaches for personalized RyR-targeted therapeutics.

Abstract 1019: Intracellular Calcium Cycling Mediates Proliferation and Differentiation of Human Cardiac Stem Cells

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Roberto Rizzi ◽  
Michael L Arcarese ◽  
Grazia Esposito ◽  
Claudia Bearzi ◽  
Justin A Korn ◽  
...  
Keyword(s):  
Stem Cells ◽  
Ryanodine Receptors ◽  
Cardiac Cells ◽  
Brdu Incorporation ◽  
Signalling Pathways ◽  
Cardiac Stem Cells ◽  
Proliferation And Differentiation ◽  
Intracellular Ca

Human cardiac stem cells (hCSCs) are self-renewing, clonogenic and have the ability to differentiate into myocytes, smooth muscle and endothelial cells in vitro and in vivo. Since Ca 2+ plays a crucial role in mechanotransduction and activation of signalling pathways in mature cardiac cells, intracellular Ca 2+ cycling was studied in hCSCs to determine the function of this cation in cell division and commitment to the myocyte lineage. For this purpose, hCSCs were exposed to conditions favouring proliferation and differentiation and affecting intracellular Ca 2+ homeostasis. Moreover, hCSCs were loaded with Fluo-3 and intracellular Ca 2+ levels were monitored by 2-photon microscopy. hCSCs presented spontaneous Ca 2+ spikes mediated by Ca 2+ release from the endoplasmic reticulum (ER). ATP and histamine, which stimulate InsP 3 R-mediated ER Ca 2+ release, increased the occurrence of spikes leading to oscillations in intracellular Ca 2+ . 2-APB, an antagonist of InsP 3 R, inhibited spike formation and oscillatory events. Ryanodine, which acts on the ryanodine receptors, did not alter intracellular Ca 2+ and thapsigargin, a Ca 2+ pump blocker, prevented spontaneous and induced ER Ca 2+ release. Store operated capacitative Ca 2+ entry was evoked by increasing extracellular Ca 2+ after depletion of the ER. Ca 2+ entry was blocked by lanthanum. Additionally, patch-clamp experiments indicated the absence of the voltage-activated L-type Ca 2+ current in hCSCs. Exposure of hCSCs to IGF-1 triggered acutely Ca 2+ spikes and increased chronically their occurrence. Over a period of 24 hours, IGF-1 resulted in more than 100% increase in the proliferation of hCSCs measured by BrdU labelling. Similarly, ATP enhanced proliferation of hCSC by ~60%. Importantly, incubation with 2-APB reduced by ~50% BrdU incorporation and abolished the effect of IGF-1 and ATP on both Ca 2+ spikes and cell proliferation. In the presence of differentiating medium, the frequency of Ca 2+ spikes in active hCSCs increased significantly. Additionally, enhanced Ca 2+ cycling increased the number of hCSCs committed to the myocyte lineage, while attenuations in this phenomenon blunted hCSC differentiation. Thus, InsP 3 R-mediated Ca 2+ spikes play an obligatory role in hCSC growth and differentiation.

scholarly journals Calcium dynamics underlying the myogenic response of the renal afferent arteriole

2014 ◽  
Vol 306 (1) ◽  
pp. F34-F48 ◽  
Author(s):  
Aurélie Edwards ◽  
Anita T. Layton
Keyword(s):  
Blood Pressure ◽  
Muscle Tone ◽  
Ryanodine Receptors ◽  
Myogenic Response ◽  
Afferent Arteriole ◽  
Luminal Diameter ◽  
Intracellular Ca ◽  
Experimental Findings ◽  
Induced Changes

The renal afferent arteriole reacts to an elevation in blood pressure with an increase in muscle tone and a decrease in luminal diameter. This effect, known as the myogenic response, is believed to stabilize glomerular filtration and to protect the glomerulus from systolic blood pressure increases, especially in hypertension. To study the mechanisms underlying the myogenic response, we developed a mathematical model of intracellular Ca2+ signaling in an afferent arteriole smooth muscle cell. The model represents detailed transmembrane ionic transport, intracellular Ca2+ dynamics, the kinetics of myosin light chain phosphorylation, and the mechanical behavior of the cell. It assumes that the myogenic response is initiated by pressure-induced changes in the activity of nonselective cation channels. Our model predicts spontaneous vasomotion at physiological luminal pressures and KCl- and diltiazem-induced diameter changes comparable to experimental findings. The time-periodic oscillations stem from the dynamic exchange of Ca2+ between the cytosol and the sarcoplasmic reticulum, coupled to the stimulation of Ca2+-activated potassium (KCa) and chloride (ClCa) channels, and the modulation of voltage-activated L-type channels; blocking sarco/endoplasmic reticulum Ca2+ pumps, ryanodine receptors (RyR), KCa, ClCa, or L-type channels abolishes these oscillations. Our results indicate that the profile of the myogenic response is also strongly dependent on the conductance of ClCa and L-type channels, as well as the activity of plasmalemmal Ca2+ pumps. Furthermore, inhibition of KCa is not necessary to induce myogenic contraction. Lastly, our model suggests that the kinetic behavior of L-type channels results in myogenic kinetics that are substantially faster during constriction than during dilation, consistent with in vitro observations (Loutzenhiser R, Bidani A, Chilton L. Circ. Res. 90: 1316–1324, 2002).

Induction of LTD in the Dentate Gyrus In Vitro Is NMDA Receptor Independent, but Dependent on Ca2+ Influx via Low-Voltage–Activated Ca2+ Channels and Release of Ca2+ From Intracellular Stores

1997 ◽  
Vol 77 (2) ◽  
pp. 812-825 ◽  
Author(s):  
Yue Wang ◽  
Michael J. Rowan ◽  
Roger Anwyl
Keyword(s):  
Nmda Receptor ◽  
Dentate Gyrus ◽  
Low Voltage ◽  
Ryanodine Receptors ◽  
Long Term Potentiation ◽  
Ruthenium Red ◽  
High Concentration ◽  
Intracellular Ca

Wang, Yue, Michael J. Rowan, and Roger Anwyl. Induction of LTD in the dentate gyrus in vitro is NMDA receptor independent, but dependent on Ca2+ influx via low-voltage-activated Ca2+ channels and release of Ca2+ from intracellular stores. J. Neurophysiol. 77: 812–825, 1997. The mechanisms of the induction of long-term depression (LTD) of field excitatory postsynaptic potentials (EPSPs) and whole cell patch-clamped excitatory postsynaptic currents (EPSCs) were studied in the dentate gyrus of the rat hippocampus. LTD of field EPSPs measuring 40% of control at 30 min poststimulation was induced by low-frequency stimulation consisting of 900 pulses at 1 Hz. LTD of EPSCs measuring 37% of control was induced by a pairing procedure consisting of 60 pulses at 1 Hz applied under voltage clamp at a holding potential of −40 mV. The induction of LTD of field EPSPs was dependent on an influx of extracellular calcium, being reduced in a low-Ca2+ (0.8 mM) medium. However, substantial LTD (26%) was still induced in such a medium, demonstrating the relatively low sensitivity of LTD induction to the level of extracellular Ca2+. A high concentration of the N-methyl-d-aspartate receptor antagonist d(−)-2-amino-5-phosphonopentanoic acid (d-AP5) (100 μM) did not significantly inhibit the induction of LTD of EPSCs evoked by the intracellular pairing procedure. d-AP5 partially reduced the magnitude of LTD of field EPSPs, but substantial LTD was still induced in the presence of AP5. The induction of LTD was strongly inhibited by Ni2+ (50 μM) but not by nifedipine (10 μM), indicating that Ca2+ influx via T-type, but not L-type, Ca2+ channels is required for the induction of LTD. The induction of LTD was strongly inhibited by thapsigargin, an agent known to deplete intracellular Ca2+ stores. The induction of LTD, but not long-term potentiation (LTP), was also strongly inhibited by ruthenium red, an agent known to block the ryanodine receptors located on intracellular Ca2+ stores. These results demonstrate that Ca2+ release from intracellular Ca2+ stores is required for the induction of LTD, but not LTP. The results of the present experiments suggest that the induction of LTD involves the entry of Ca2+ via low-voltage–activated voltage-gated Ca2+ channels followed by release of Ca2+ from intracellular ryanodine-receptor-sensitive Ca2+ stores.

scholarly journals Effect of memantine, an anti-Alzheimer’s drug, on rodent microglial cells in vitro

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Toru Murakawa-Hirachi ◽  
Yoshito Mizoguchi ◽  
Masahiro Ohgidani ◽  
Yoshinori Haraguchi ◽  
Akira Monji
Keyword(s):  
Neuronal Death ◽  
Phagocytic Activity ◽  
Microglial Cell ◽  
Cell Function ◽  
Microglial Cells ◽  
Phagocytosis Assay ◽  
Intracellular Ca ◽  
Β Amyloid ◽  
The Brain

AbstractThe pathophysiology of Alzheimer’s disease (AD) is related to neuroinflammatory responses mediated by microglia. Memantine, an antagonist of N-methyl-d-aspartate (NMDA) receptors used as an anti-Alzheimer’s drug, protects from neuronal death accompanied by suppression of proliferation and activation of microglial cells in animal models of AD. However, it remains to be tested whether memantine can directly affect microglial cell function. In this study, we examined whether pretreatment with memantine affects intracellular NO and Ca2+ mobilization using DAF-2 and Fura-2 imaging, respectively, and tested the effects of memantine on phagocytic activity by human β-Amyloid (1–42) phagocytosis assay in rodent microglial cells. Pretreatment with memantine did not affect production of NO or intracellular Ca2+ elevation induced by TNF in rodent microglial cells. Pretreatment with memantine also did not affect the mRNA expression of pro-inflammatory (TNF, IL-1β, IL-6 and CD45) or anti-inflammatory (IL-10, TGF-β and arginase) phenotypes in rodent microglial cells. In addition, pretreatment with memantine did not affect the amount of human β-Amyloid (1–42) phagocytosed by rodent microglial cells. Moreover, we observed that pretreatment with memantine did not affect 11 major proteins, which mainly function in the phagocytosis and degradation of β-Amyloid (1–42), including TREM2, DAP12 and neprilysin in rodent microglial cells. To the best of our knowledge, this is the first report to suggest that memantine does not directly modulate intracellular NO and Ca2+ mobilization or phagocytic activity in rodent microglial cells. Considering the neuroinflammation hypothesis of AD, the results might be important to understand the effect of memantine in the brain.

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