Ryanodine receptors mediate high intracellular Ca2+ and some myocyte damage following eccentric contractions in rat fast twitch skeletal muscle

2021 ◽  
Author(s):  
Ayaka Tabuchi ◽  
Yoshinori Tanaka ◽  
Ryo Takagi ◽  
Hideki Shirakawa ◽  
Tsubasa Shibaguchi ◽  
...  
Keyword(s):  
Muscle Damage ◽  
Ryanodine Receptors ◽  
Cytosolic Calcium ◽  
Specific Pattern ◽  
Eccentric Contractions ◽  
Cellular Processes ◽  
Area 5 ◽  
Myocyte Damage ◽  
Fast Twitch

Eccentric contractions (ECC) facilitate cytosolic calcium ion (Ca2+) release from the sarcoplasmic reticulum (SR) and Ca2+ influx from extracellular space. Ca2+ is a vital signaling messenger that regulates multiple cellular processes via its spatial and temporal concentration ([Ca2+]i) dynamics. We hypothesized that: 1) a specific pattern of spatial/temporal intramyocyte Ca2+ dynamics portends muscle damage following ECC, and 2) these dynamics would be regulated by the ryanodine receptor (RyR). [Ca2+]i in the tibialis anterior muscles of anesthetized adult Wistar rats was measured by ratiometric (i.e. ratio, R, 340/380 nm excitation) in vivo bioimaging with Fura-2 pre-ECC and at 5 and 24 hours post-ECC (5 x 40 contractions). Rats received RyR inhibitor dantrolene (DAN; 10 mg/kg i.p.) immediately post-ECC (+DAN). Muscle damage was evaluated by histological analysis on hematoxylin-eosin stained muscle sections. Compared to control (CONT, no ECC), [Ca2+]i distribution was heterogeneous with increased % total area of high [Ca2+]i sites (operationally defined as R > 1.39 i.e., > 1 SD of mean control) 5 hours post-ECC (CONT, 14.0 ± 8.0; ECC5h: 52.0 ± 7.4%, p < 0.01). DAN substantially reduced the high [Ca2+]i area 5 hours post-ECC (ECC5h+DAN: 6.4 ± 3.1%, p < 0.01) and myocyte damage (ECC24h, 63.2 ± 1.0%; ECC24h+DAN, 29.1 ± 2.2%, p < 0.01). Temporal and spatially-amplified [Ca2+]i fluctuations occurred regardless of DAN (ECC vs ECC+DAN, p > 0.05). These results suggest that the RyR-mediated local high [Ca2+]i itself is related to the magnitude of muscle damage while the [Ca2+]i fluctuation is an RyR-independent phenomenon.

Orthograde signal of dihydropyridine receptor increases Ca2+ leakage after repeated contractions in rat fast-twitch muscles in vivo

2021 ◽  
Vol 320 (5) ◽  
pp. C806-C821
Author(s):  
Daiki Watanabe ◽  
Masanobu Wada
Keyword(s):  
Sarcoplasmic Reticulum ◽  
High Intensity ◽  
Ryanodine Receptors ◽  
Inhibitory Effect ◽  
Skinned Fibers ◽  
Inhibitory Effects ◽  
Dihydropyridine Receptors ◽  
Gastrocnemius Muscles ◽  
Fast Twitch

The purpose of this study was to investigate the mechanism underlying sarcoplasmic reticulum (SR) Ca2+ leakage after in vivo contractions. Rat gastrocnemius muscles were electrically stimulated in vivo, and then mechanically skinned fibers and SR microsomes were prepared from the muscles excised 30 min after repeated high-intensity contractions. The mechanically skinned fibers maintained the interaction between dihydropyridine receptors (DHPRs) and ryanodine receptors (RyRs), whereas the SR microsomes did not. Interestingly, skinned fibers from the stimulated muscles showed increased SR Ca2+ leakage, whereas Ca2+ leakage decreased in SR microsomes from the stimulated muscles. To enhance the orthograde signal of DHPRs, SR Ca2+ leakage in the skinned fiber was measured 1) under a continuously depolarized condition and 2) in the presence of nifedipine. As a result, in either of the two conditions, SR Ca2+ leakage in the rested fibers reached a level similar to that in the stimulated fibers. Furthermore, the increased SR Ca2+ leakage from the stimulated fibers was alleviated by treatment with 1 mM tetracaine (Tet) but not by treatment with 3 mM free Mg2+ (3 Mg). Tet exerted a greater inhibitory effect on the DHPR signal to RyR than 3 Mg, although their inhibitory effects on RyR were almost similar. These results suggest that the increased Ca2+ leakage after muscle contractions is mainly caused by the orthograde signal of DHPRs to RyRs.

scholarly journals Phytoecdysteroids Accelerate Recovery of Skeletal Muscle Function Following in vivo Eccentric Contraction-Induced Injury in Adult and Old Mice

2021 ◽  
Vol 2 ◽  
Author(s):  
Kevin A. Zwetsloot ◽  
R. Andrew Shanely ◽  
Joshua S. Godwin ◽  
Charles F. Hodgman
Keyword(s):  
Skeletal Muscle ◽  
Muscle Damage ◽  
Muscle Function ◽  
Recovery Period ◽  
Eccentric Contraction ◽  
Eccentric Contractions ◽  
Post Injury ◽  
Skeletal Muscle Function ◽  
Old Mice

Background: Eccentric muscle contractions are commonly used in exercise regimens, as well as in rehabilitation as a treatment against muscle atrophy and weakness. If repeated multiple times, eccentric contractions may result in skeletal muscle injury and loss of function. Skeletal muscle possesses the remarkable ability to repair and regenerate after an injury or damage; however, this ability is impaired with aging. Phytoecdysteroids are natural plant steroids that possess medicinal, pharmacological, and biological properties, with no adverse side effects in mammals. Previous research has demonstrated that administration of phytoecdysteroids, such as 20-hydroxyecdysone (20E), leads to an increase in protein synthesis signaling and skeletal muscle strength.Methods: To investigate whether 20E enhances skeletal muscle recovery from eccentric contraction-induced damage, adult (7–8 mo) and old (26–27 mo) mice were subjected to injurious eccentric contractions (EC), followed by 20E or placebo (PLA) supplementation for 7 days. Contractile function via torque-frequency relationships (TF) was measured three times in each mouse: pre- and post-EC, as well as after the 7-day recovery period. Mice were anesthetized with isoflurane and then electrically-stimulated isometric contractions were performed to obtain in vivo muscle function of the anterior crural muscle group before injury (pre), followed by 150 EC, and then again post-injury (post). Following recovery from anesthesia, mice received either 20E (50 mg•kg−1 BW) or PLA by oral gavage. Mice were gavaged daily for 6 days and on day 7, the TF relationship was reassessed (7-day).Results: EC resulted in significant reductions of muscle function post-injury, regardless of age or treatment condition (p &lt; 0.001). 20E supplementation completely recovered muscle function after 7 days in both adult and old mice (pre vs. 7-day; p &gt; 0.05), while PLA muscle function remained reduced (pre vs. 7-day; p &lt; 0.01). In addition, histological markers of muscle damage appear lower in damaged muscle from 20E-treated mice after the 7-day recovery period, compared to PLA.Conclusions: Taken together, these findings demonstrate that 20E fully recovers skeletal muscle function in both adult and old mice just 7 days after eccentric contraction-induced damage. However, the underlying mechanics by which 20E contributes to the accelerated recovery from muscle damage warrant further investigation.

Effect of vitamin D status on the rapid actions of 1,25-dihydroxycholecalciferol in rat colonic membranes

1992 ◽  
Vol 262 (6) ◽  
pp. G945-G953
Author(s):  
R. K. Wali ◽  
C. L. Baum ◽  
M. D. Sitrin ◽  
M. J. Bolt ◽  
P. K. Dudeja ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Vitamin D ◽  
Signal Transduction Pathway ◽  
Cytosolic Calcium ◽  
Dietary Vitamin ◽  
Vitamin D Status ◽  
Cellular Processes ◽  
Bethanechol Chloride

Recent studies from our laboratory have demonstrated that the in vitro addition of 1,25-dihydroxycholecalciferol [1,25(OH)2D3] rapidly (seconds to minutes) stimulated membrane phosphoinositide turnover, translocated protein kinase C from the cytosolic to particulate fraction, increased cytosolic calcium ([Ca2+]i), and decreased cytoplasmic pH (pHi) via inhibition of Na(+)-H+ exchange in rat colonic epithelium of dietary vitamin D-sufficient rats and in Caco-2 cells. In contrast to these prior findings, in the present experiments, 1,25(OH)2D3 failed to elicit any of these colonic biochemical responses in vitamin D-deficient animals. Bethanechol chloride also failed to alter this signal transduction pathway, [Ca2+]i, or pHi. In vivo administration of this hormone for 5-7 days, moreover, to vitamin D-deficient animals restored the rapid biochemical effects of in vitro 1,25(OH)2D3 and bethanechol chloride. These studies, therefore, indicate that alterations in the vitamin D status of rats modulate the action of 1,25(OH)2D3 and other agents on the colonic phosphoinositide signal transduction system and on [Ca2+]i, which, in turn, may influence important cellular processes in this organ such as Na(+)-H+ exchange.

Sex differences in intracellular Ca2+ accumulation following eccentric contractions of rat skeletal muscle in vivo

2010 ◽  
Vol 299 (4) ◽  
pp. R1006-R1012 ◽  
Author(s):  
Takashi Sonobe ◽  
Tadakatsu Inagaki ◽  
Mizuki Sudo ◽  
David C. Poole ◽  
Yutaka Kano
Keyword(s):  
Skeletal Muscle ◽  
Muscle Damage ◽  
Eccentric Exercise ◽  
Muscle Length ◽  
Eccentric Contractions ◽  
Intermediate Response ◽  
The Difference ◽  
Exercise Induced ◽  
Resting Muscle

It is commonly believed that estrogen and sex influences play significant effects in skeletal muscle damage following eccentric exercise. The mechanistic bases for this sex-specific phenomenon remain to be resolved. The muscle damage has been linked to loss of Ca2+ homeostasis and resultant intramyocyte Ca2+ ([Ca2+]i) accumulation; therefore, we tested the hypothesis that the greater eccentric exercise-induced muscle damage in males would be associated with more pronounced [Ca2+]i accumulation. The intact spinotrapezius muscle of adult Wistar rats [male, female, and ovariectomized (OVX)—to investigate the effects of estrogen] was exteriorized. Tetanic eccentric contractions (100 Hz, 700-ms duration, 20 contractions/min for a total of 10 sets of 50 contractions) were elicited by electrical stimulation during synchronized muscle stretch of 10% resting muscle length. The fluorescence ratio (F340/F380 nm) was determined from images captured following each set of contractions, and fura-2 AM was used to estimate [Ca2+]i and changes thereof. Following eccentric contractions, [Ca2+]i increased significantly in male (42.8 ± 5.3%, P < 0.01) but not in female (9.4 ± 3.5%) rats. OVX evidenced an intermediate response (17.0 ± 1.2%) that remained significantly reduced compared with males. These results demonstrate that females maintain [Ca2+]i homeostasis following novel eccentric contractions, whereas males do not, which is consistent with a role for elevated [Ca2+]i in eccentric exercise-induced muscle damage. The presence of normal estrogen levels is not obligatory for the difference between the sexes.

miR-125b enhances metastasis and progression of cancer via the TXNIP and HIF1α pathway in pancreatic cancer

2021 ◽  
pp. 1-12
Author(s):  
Pengli Wang ◽  
Dan Zheng ◽  
Hongyang Qi ◽  
Qi Gao
Keyword(s):  
Pancreatic Cancer ◽  
Hypoxia Inducible Factor ◽  
Immunofluorescence Assay ◽  
Luciferase Assay ◽  
Interacting Protein ◽  
Over Expression ◽  
Thioredoxin Interacting Protein ◽  
Cellular Processes ◽  
And Migration

BACKGROUND: MicroRNAs (miRNAs) play potential role in the development of various types of cancer conditions including pancreatic cancer (PC) targeting several cellular processes. Present study was aimed to evaluate function of miR-125b and the mechanism involved in PC. METHODS: Cell migration, MTT and BrdU study was done to establish the migration capability, cell viability and cell proliferation respectively. Binding sites for miR-125b were recognized by luciferase assay, expression of protein by western blot and immunofluorescence assay. In vivo study was done by BALB/c nude xenograft mice for evaluating the function of miR-125b. RESULTS: The study showed that expression of miR-125b was elevated in PC cells and tissues, and was correlated to proliferation and migration of cells. Also, over-expression of miR-125b encouraged migration, metastasis and proliferation of BxPC-3 cells, the suppression reversed it. We also noticed that thioredoxin-interacting protein (TXNIP) was the potential target of miR-125b. The outcomes also suggested that miR-125b governed the expression of TXNIP inversely via directly attaching to the 3′-UTR activating hypoxia-inducible factor 1α (HIF1α). Looking into the relation between HIF1α and TXNIP, we discovered that TXNIP caused the degradation and export of HIF1α by making a complex with it. CONCLUSION: The miR-125b-TXNIP-HIF1α pathway may serve useful strategy for diagnosing and treating PC.

scholarly journals Fibrosis after Myocardial Infarction: An Overview on Cellular Processes, Molecular Pathways, Clinical Evaluation and Prognostic Value

2021 ◽  
Vol 9 (1) ◽  
pp. 16
Author(s):  
Renato Francesco Maria Scalise ◽  
Rosalba De Sarro ◽  
Alessandro Caracciolo ◽  
Rita Lauro ◽  
Francesco Squadrito ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Signaling Pathways ◽  
Ventricular Dysfunction ◽  
Healing Process ◽  
Molecular Signaling ◽  
Cellular Processes ◽  
Molecular Signaling Pathways ◽  
Fibrotic Scar ◽  
Life Threatening

The ischemic injury caused by myocardial infarction activates a complex healing process wherein a powerful inflammatory response and a reparative phase follow and balance each other. An intricate network of mediators finely orchestrate a large variety of cellular subtypes throughout molecular signaling pathways that determine the intensity and duration of each phase. At the end of this process, the necrotic tissue is replaced with a fibrotic scar whose quality strictly depends on the delicate balance resulting from the interaction between multiple actors involved in fibrogenesis. An inflammatory or reparative dysregulation, both in term of excess and deficiency, may cause ventricular dysfunction and life-threatening arrhythmias that heavily affect clinical outcome. This review discusses cellular process and molecular signaling pathways that determine fibrosis and the imaging technique that can characterize the clinical impact of this process in-vivo.

scholarly journals Zebrafish Models of Autosomal Recessive Ataxias

Cells ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 836
Author(s):  
Ana Quelle-Regaldie ◽  
Daniel Sobrido-Cameán ◽  
Antón Barreiro-Iglesias ◽  
María Jesús Sobrido ◽  
Laura Sánchez
Keyword(s):  
Animal Models ◽  
Autosomal Recessive ◽  
Molecular Mechanisms ◽  
System Development ◽  
Rapid Development ◽  
Nervous System Development ◽  
Central Nervous System Development ◽  
Cellular Processes ◽  
Recessive Disorders

Autosomal recessive ataxias are much less well studied than autosomal dominant ataxias and there are no clearly defined systems to classify them. Autosomal recessive ataxias, which are characterized by neuronal and multisystemic features, have significant overlapping symptoms with other complex multisystemic recessive disorders. The generation of animal models of neurodegenerative disorders increases our knowledge of their cellular and molecular mechanisms and helps in the search for new therapies. Among animal models, the zebrafish, which shares 70% of its genome with humans, offer the advantages of being small in size and demonstrating rapid development, making them optimal for high throughput drug and genetic screening. Furthermore, embryo and larval transparency allows to visualize cellular processes and central nervous system development in vivo. In this review, we discuss the contributions of zebrafish models to the study of autosomal recessive ataxias characteristic phenotypes, behavior, and gene function, in addition to commenting on possible treatments found in these models. Most of the zebrafish models generated to date recapitulate the main features of recessive ataxias.

scholarly journals Considerations when investigating lncRNA function in vivo

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Andrew R Bassett ◽  
Asifa Akhtar ◽  
Denise P Barlow ◽  
Adrian P Bird ◽  
Neil Brockdorff ◽  
...  
Keyword(s):  
Normal Cell ◽  
Regulatory Elements ◽  
Genomic Locus ◽  
Cellular Processes ◽  
Cell Processes ◽  
Non Coding Rnas ◽  
Per Se ◽  
Dna Regulatory Elements

Although a small number of the vast array of animal long non-coding RNAs (lncRNAs) have known effects on cellular processes examined in vitro, the extent of their contributions to normal cell processes throughout development, differentiation and disease for the most part remains less clear. Phenotypes arising from deletion of an entire genomic locus cannot be unequivocally attributed either to the loss of the lncRNA per se or to the associated loss of other overlapping DNA regulatory elements. The distinction between cis- or trans-effects is also often problematic. We discuss the advantages and challenges associated with the current techniques for studying the in vivo function of lncRNAs in the light of different models of lncRNA molecular mechanism, and reflect on the design of experiments to mutate lncRNA loci. These considerations should assist in the further investigation of these transcriptional products of the genome.

Stanniocalcin-1, an inhibitor of macrophage chemotaxis and chemokinesis

2004 ◽  
Vol 286 (2) ◽  
pp. F356-F362 ◽  
Author(s):  
John Kanellis ◽  
Roger Bick ◽  
Gabriela Garcia ◽  
Luan Truong ◽  
Chun Chui Tsao ◽  
...  
Keyword(s):  
Inflammatory Response ◽  
Intracellular Calcium ◽  
In Vivo Studies ◽  
Cellular Processes ◽  
Multiple Organs ◽  
Chemotactic Protein ◽  
Stromal Cell Derived Factor ◽  
Mammalian Counterpart

In macrophages, changes in intracellular calcium have been associated with activation of cellular processes that regulate cell adhesion and motility and are important for the response of macrophages to antigenic stimuli. The mammalian counterpart of the fish calcium-regulating hormone stanniocalcin-1 (STC1) is expressed in multiple organs including the thymus and spleen, and hence, we hypothesized that it may have a role in modulating the immune/inflammatory response. Using murine macrophage-like (RAW264.7) and human monoblast-like (U937) cells to study chemotaxis in vitro, we found that STC1 attenuated chemokinesis and diminished the chemotactic response to monocyte chemotactic protein-1 (MCP-1) and stromal cell-derived factor-1α. Consistent with these findings, STC1 blunted the rise in intracellular calcium following MCP-1 stimulation in RAW264.7 cells. In vivo studies suggested differential expression of STC1 in obstructed kidney and localization to macrophages. MCP-1 and STC1 transcripts were both upregulated following ureteric obstruction, suggesting a functional association between the two genes. Our data suggest a role for mammalian STC1 in modulating the immune/inflammatory response.

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