Calcium transients during Fc receptor-mediated and nonspecific phagocytosis by murine peritoneal macrophages.

Studies with populations of macrophages have produced conflicting results concerning the possibility that the concentration of intracellular ionized calcium [( Ca2+]i) may act as an important mediator for phagocytosis. Since asynchronous changes in [Ca2+]i in individual cells undergoing phagocytosis may be averaged to undetectability in population studies, we studied single adhering murine macrophages using fura-2 and our previously described digital imaging system. The proportion of macrophages phagocytosing IgG-coated latex beads was greater than for uncoated beads (percent phagocytosing cells: 71 +/- 7 vs. 27 +/- 7, P less than 0.01). Phagocytosis of IgG-coated and uncoated beads was always associated with a calcium transient that preceded the initiation of phagocytosis. No calcium transients were detected in cells that bound but did not phagocytose beads. Four major differences between Fc receptor-mediated and nonspecific phagocytosis were detected: (a) the duration of calcium transients was longer for nonspecific phagocytosis compared with Fc receptor-mediated phagocytosis (69.9 +/- 10.2 vs. 48.7 +/- 4.7 s, P less than 0.05) and the magnitude of calcium transients was less for nonspecific phagocytosis (178 +/- 43 vs. 349 +/- 53 nM, P less than 0.05); (b) removal of extracellular calcium abolished the calcium transients associated with nonspecific phagocytosis but had no effect on those associated with receptor-mediated phagocytosis; (c) in the absence of extracellular calcium, buffering intracellular calcium with a chelator reduced Fc receptor-mediated phagocytosis but had no additive inhibitory effect on nonspecific phagocytosis; and (d) inhibition of protein kinase C (PKC) with staurosporine inhibited nonspecific phagocytosis but had no effect on receptor-mediated phagocytosis. Our observations suggest that despite both types of phagocytosis being associated with intracellular calcium transients, the role played by intracellular calcium in the signaling pathways may differ for Fc receptor-mediated and nonspecific phagocytosis by elicited murine macrophages.

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Caffeine attenuates contraction-induced diminutions of the intracellular calcium transient in mouse lumbrical muscle ex vivo

Canadian Journal of Physiology and Pharmacology ◽

10.1139/cjpp-2018-0658 ◽

2019 ◽

Vol 97 (5) ◽

pp. 429-435 ◽

Cited By ~ 2

Author(s):

Ian C. Smith ◽

Rene Vandenboom ◽

A. Russell Tupling

Keyword(s):

Skeletal Muscle ◽

Intracellular Calcium ◽

Calcium Release ◽

Ex Vivo ◽

Calcium Transient ◽

Calcium Transients ◽

Inotropic Effects ◽

Intracellular Calcium Transient ◽

Lumbrical Muscle ◽

Lumbrical Muscles

The amount of calcium released from the sarcoplasmic reticulum in skeletal muscle rapidly declines during repeated twitch contractions. In this study, we test the hypothesis that caffeine can mitigate these contraction-induced declines in calcium release. Lumbrical muscles were isolated from male C57BL/6 mice and loaded with the calcium-sensitive indicator, AM-furaptra. Muscles were then stimulated at 8 Hz for 2.0 s in the presence or absence of 0.5 mM caffeine, at either 30 °C or 37 °C. The amplitude and area of the furaptra-based intracellular calcium transients and force produced during twitch contractions were calculated. For each of these measures, the values for twitch 16 relative to twitch 1 were higher in the presence of caffeine than in the absence of caffeine at both temperatures. We conclude that caffeine can attenuate contraction-induced diminutions of calcium release during repeated twitch contractions, thereby contributing to the inotropic effects of caffeine.

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Inhibition of Extracellular Calcium Influx Results in Enhanced IL-12 Production in LPS-Treated Murine Macrophages by Downregulation of the CaMKKβ-AMPK-SIRT1 Signaling Pathway

Mediators of Inflammation ◽

10.1155/2016/6152713 ◽

2016 ◽

Vol 2016 ◽

pp. 1-15 ◽

Cited By ~ 9

Author(s):

Xin Liu ◽

Ning Wang ◽

Yuanfeng Zhu ◽

Yongjun Yang ◽

Xiaoli Chen ◽

...

Keyword(s):

Signaling Pathway ◽

Calcium Influx ◽

Peritoneal Macrophages ◽

Extracellular Calcium ◽

Negative Regulator ◽

Sirtuin 1 ◽

Primary Sources ◽

Ampk Activation ◽

Murine Macrophages ◽

Calcium Dependent

Activated macrophages are the primary sources of IL-12, a key cytokine bridging innate and adaptive immunity. However, macrophages produce low amounts of IL-12 upon stimulation and the underlying regulatory mechanism remains unclear. In this study, we found a new calcium-dependent mechanism that controlled IL-12 production in LPS-treated murine macrophages. First, LPS was demonstrated to induce extracellular calcium entry in murine peritoneal macrophages and inhibition of calcium influx resulted in marked enhancement in IL-12 production. Then, withdrawal of extracellular calcium was found to suppress CaMKKβand AMPK activation triggered by LPS while chemical inhibition or genetic knockdown of these two kinases augmented LPS induced IL-12 production. AMPK activation increased the NAD+/NADH ratio and activated Sirtuin 1 (SIRT1), a NAD+-dependent deacetylating enzyme and negative regulator of inflammation. Chemical inhibitor or siRNA of SIRT1 enhanced IL-12 release while its agonist suppressed IL-12 production. Finally, it was found that SIRT1 selectively affected the transcriptional activity of NF-κB which thereby inhibited IL-12 production. Overall, our study demonstrates a new role of transmembrane calcium mobilization in immunity modulation such that inhibition of calcium influx leads to impaired activation of CaMKKβ-AMPK-SIRT1 signaling pathway which lifts restriction on NF-κB activation and results in enhanced IL-12 production.

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Influence of Plasma Glucose Concentration on Rat Brain Extracellular Calcium Transients during Spreading Depression

Journal of Cerebral Blood Flow & Metabolism ◽

10.1038/jcbfm.1993.21 ◽

1993 ◽

Vol 13 (1) ◽

pp. 179-182 ◽

Cited By ~ 29

Author(s):

Gunilla Gidö ◽

Kenichiro Katsura ◽

Tibor Kristian ◽

Bo K. Siesjö

Keyword(s):

Plasma Glucose ◽

Glucose Concentration ◽

Spreading Depression ◽

Calcium Transient ◽

Extracellular Calcium ◽

Plasma Glucose Concentration ◽

Calcium Transients ◽

Ischemic Lesion ◽

Dc Potential ◽

Lower Plasma Glucose

The objective of this study was to establish whether tissues that are energy compromised, but not energy depleted, demonstrate exaggerated calcium transients when subjected to membrane depolarizations of the spreading depression (SD) type. Anesthetized and artificially ventilated rats were given insulin in order to induce progressively lower plasma glucose concentrations. Spreading depression was elicited by local application of KCl; extracellular calcium concentration (Ca2+e) as well as direct current (DC) potential were recorded. When plasma glucose concentration fell below ∼3 m M, the duration of the Ca2+e transient gradually increased to values exceeding 500% of control. The increase was associated with a corresponding increase in the duration of the DC potential shift, but the amplitude of the Ca2+e transient did not change. It is concluded that a restriction of glucose (or oxygen) supply, as occurs in hypoglycemia (or hypoxia), prolongs the calcium transient associated with depolarization of the SD type, even though tissue phosphocreatine and ATP concentrations are normal. The results support the contention that repeated depolarizations, occurring in the penumbral zone of a focal ischemic lesion, could lead to calcium-related damage.

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Reply to “TRPA1-dependent calcium transients and CGRP release in DRG neurons require extracellular calcium”

The Journal of Cell Biology ◽

10.1083/jcb.202004017 ◽

2020 ◽

Vol 219 (6) ◽

Author(s):

Bing Liu ◽

Muhammad Younus ◽

Suhua Sun ◽

Yiman Li ◽

Yuan Wang ◽

...

Keyword(s):

Dorsal Root Ganglion ◽

Intracellular Calcium ◽

Dorsal Root ◽

Extracellular Calcium ◽

Dorsal Root Ganglion Neurons ◽

Calcium Transients ◽

Drg Neurons ◽

Cgrp Release ◽

Ganglion Neurons

In this issue, Gebhardt et al. (2020. J. Cell Biol.https://doi.org/10.1083/jcb.201702151) express interest in our recently published work (Shang et al. 2016. J. Cell Biol.https://doi.org/10.1083/jcb.201603081). Here, we would like to address their concerns regarding the lysosomal TRPA1-mediated intracellular calcium transients in dorsal root ganglion neurons.

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Impaired mitochondria and intracellular calcium transients in the salivary glands of obese rats

Applied Physiology Nutrition and Metabolism ◽

10.1139/apnm-2016-0545 ◽

2017 ◽

Vol 42 (4) ◽

pp. 420-429 ◽

Cited By ~ 6

Author(s):

Jitjiroj Ittichaicharoen ◽

Nattayaporn Apaijai ◽

Pongpan Tanajak ◽

Piangkwan Sa-nguanmoo ◽

Nipon Chattipakorn ◽

...

Keyword(s):

Oxidative Stress ◽

Insulin Resistance ◽

Intracellular Calcium ◽

Salivary Glands ◽

Mitochondrial Function ◽

Calcium Transient ◽

Salivary Flow ◽

Calcium Transients ◽

Intracellular Calcium Transient

Long-term consumption of a high-fat diet (HFD) causes not only obese-insulin resistance, but is also associated with mitochondrial dysfunction in several organs. However, the effect of obese-insulin resistance on salivary glands has not been investigated. We hypothesized that obese-insulin resistance induced by HFD impaired salivary gland function by reducing salivation, increasing inflammation, and fibrosis, as well as impairing mitochondrial function and calcium transient signaling. Male Wistar rats (200–220 g) were fed either a ND or an HFD (n = 8/group) for 16 weeks. At the end of week 16, salivary flow rates, metabolic parameters, and plasma oxidative stress were determined. Rats were then sacrificed and submandibular glands were removed to determine inflammation, fibrosis, apoptosis, mitochondrial function and dynamics, and intracellular calcium transient signaling. Long-term consumption of an HFD caused obese-insulin resistance and increased oxidative stress, fibrosis, inflammation, and apoptosis in the salivary glands. In addition, impaired mitochondrial function, as indicated by increased mitochondrial reactive oxygen species, mitochondrial membrane depolarization, and mitochondrial swelling in salivary glands and impaired intracellular calcium regulation, as indicated by a reduced intracellular calcium transient rising rate, decay rates, and amplitude of salivary acinar cells, were observed in HFD-fed rats. However, salivary flow rate and level of aquaporin 5 protein were not different between both groups. Although HFD consumption did not affect salivation, it caused obese-insulin resistance, leading to pathophysiological alteration of salivary glands, including impaired intracellular calcium transients, increased oxidative stress and inflammation, and salivary mitochondrial dysfunction.

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Intracellular calcium handling heterogeneities in intact guinea pig hearts

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00374.2003 ◽

2004 ◽

Vol 286 (2) ◽

pp. H648-H656 ◽

Cited By ~ 35

Author(s):

Rodolphe P. Katra ◽

Etienne Pruvot ◽

Kenneth R. Laurita

Keyword(s):

Guinea Pig ◽

Intracellular Calcium ◽

Calcium Release ◽

Optical Mapping ◽

Contractile Function ◽

Calcium Transient ◽

Calcium Transients ◽

Calcium Handling ◽

Excitation Light ◽

Intact Heart

Regional heterogeneities of ventricular repolarizing currents and their role in arrhythmogenesis have received much attention; however, relatively little is known regarding heterogeneities of intracellular calcium handling. Because repolarization properties and contractile function are heterogeneous from base to apex of the intact heart, we hypothesize that calcium handling is also heterogeneous from base to apex. To test this hypothesis, we developed a novel ratiometric optical mapping system capable of measuring calcium fluorescence of indo-1 at two separate wavelengths from 256 sites simultaneously. With the use of intact Langendorff-perfused guinea pig hearts, ratiometric calcium transients were recorded under normal conditions and during administration of known inotropic agents. Ratiometric calcium transients were insensitive to changes in excitation light intensity and fluorescence over time. Under control conditions, calcium transient amplitude near the apex was significantly larger (60%, P < 0.01) compared with the base. In contrast, calcium transient duration was significantly longer (7.5%, P < 0.03) near the base compared with the apex. During isoproterenol (0.05 μM) and verapamil (2.5 μM) administration, ratiometric calcium transients accurately reflected changes in contractile function, and, the direction of base-to-apex heterogeneities remained unchanged compared with control. Ratiometric optical mapping techniques can be used to accurately quantify heterogeneities of calcium handling in the intact heart. Significant heterogeneities of calcium release and sequestration exist from base to apex of the intact heart. These heterogeneities are consistent with base-to-apex heterogeneities of contraction observed in the intact heart and may play a role in arrhythmogenesis under abnormal conditions.

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TRPA1-dependent calcium transients and CGRP release in DRG neurons require extracellular calcium

The Journal of Cell Biology ◽

10.1083/jcb.201702151 ◽

2020 ◽

Vol 219 (6) ◽

Cited By ~ 2

Author(s):

Lisa A. Gebhardt ◽

Tetyana I. Kichko ◽

Michael J.M. Fischer ◽

Peter W. Reeh

Keyword(s):

Intracellular Calcium ◽

Extracellular Calcium ◽

Calcium Transients ◽

Drg Neurons ◽

Cgrp Release

Shang et al. (2016. J. Cell Biol.https://doi.org/10.1083/jcb.201603081) reported that activation of lysosomal TRPA1 channels led to intracellular calcium transients and CGRP release from DRG neurons. We argue that both findings are more likely due to influx of insufficiently buffered extracellular calcium rather than lysosomal release.

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The somatotrope: an endocrine cell with functional calcium transients

Journal of Experimental Biology ◽

10.1242/jeb.139.1.169 ◽

1988 ◽

Vol 139 (1) ◽

pp. 169-179

Author(s):

M. O. Thorner ◽

R. W. Holl ◽

D. A. Leong

Keyword(s):

Intracellular Calcium ◽

Calcium Concentration ◽

Hormone Secretion ◽

Extracellular Calcium ◽

Calcium Oscillations ◽

Calcium Transients ◽

Male Rats ◽

Free Calcium ◽

Cytosolic Free Calcium ◽

Gh Secretion

Growth hormone (GH) secretion by the somatotrope is under dual regulation by the hypothalamic peptides, somatostatin (SS) and GH-releasing hormone (GHRH). Cytosolic free calcium concentration and cumulative GH release were measured simultaneously in anterior pituitary cells from adult male rats. This was made possible using a combination of digital imaging video microscopy with the fluorescent calcium indicator Fura-2 and the reverse haemolytic plaque assay (RHPA) to identify the cell type and measure hormone secretion from the cells under study. This technique allows calcium measurements to be made at very short time intervals (less than 150 ms) in single cells. Spontaneous calcium transients were demonstrated in 85% of GH plaque-forming cells. These occurred at a frequency of 2–13 min-1 and had an amplitude of 50–500 nmoll-1. The somatotropes with the largest calcium fluctuations produced the largest plaques; thus, the calcium transients appeared to correlate with hormone release. Since the somatotrope alone shows these fluctuations, the mean intracellular calcium concentration is 238 +/− 18 nmoll-1 in somatotropes and 113 +/− 8 nmoll-1 in non-somatotropes. Upon exposure to SS (1 nmoll-1) intracellular calcium fell from 200–250 nmoll-1 to 50–100 nmoll-1 with an apparent reduction in oscillations. Withdrawal of SS increased the intracellular calcium level. GHRH increased intracellular calcium but 10 nmoll-1 GHRH given simultaneously with 1 nmoll-1 SS reduced intracellular calcium to that level observed during SS alone. Thus, the SS effect on intracellular calcium predominates. The effects of SS can be mimicked by removal of extracellular calcium, or by the addition of CoCl2 (2 nmoll-1) or by verapamil (100 mumoll-1), two agents which block calcium channels. The hormone secretion index (indicated by the area of the plaque formed in RHPA) enables us to demonstrate that GHRH in this system increases GH secretion, and SS inhibits it. In combination, GHRH and SS oppose one another. Spontaneous calcium oscillations are characteristic for normal somatotropes. These oscillations are related to spontaneous hormone secretion and due to influx of calcium through ion channels in the membrane. Intracellular signalling information may be encoded in both frequency and amplitude of calcium oscillations. The actions of GHRH and SS on regulation of GH secretion are proposed to be mediated, at least in part, by regulation of intracellular cytosolic free calcium. This modulation is dependent on extracellular calcium concentrations. We are now investigating the molecular mechanisms involved in this process.

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