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Loftus FC, Shmygol A, Richardson MJE. Fine spatiotemporal activity in contracting myometrium revealed by motion-corrected calcium imaging. J Physiol 2014; 592:4447-63. [PMID: 25085893 PMCID: PMC4280886 DOI: 10.1113/jphysiol.2014.275412] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Successful childbirth depends on the occurrence of precisely coordinated uterine contractions during labour. Calcium indicator fluorescence imaging is one of the main techniques for investigating the mechanisms governing this physiological process and its pathologies. The effective spatiotemporal resolution of calcium signals is, however, limited by the motion of contracting tissue: structures of interest in the order of microns can move over a hundred times their width during a contraction. The simultaneous changes in local intensity and tissue configuration make motion tracking a non-trivial problem in image analysis and confound many of the standard techniques. This paper presents a method that tracks local motion throughout the tissue and allows for the almost complete removal of motion artefacts. This provides a stabilized calcium signal down to a pixel resolution, which, for the data examined, is in the order of a few microns. As a byproduct of image stabilization, a complete kinematic description of the contraction–relaxation cycle is also obtained. This contains novel information about the mechanical response of the tissue, such as the identification of a characteristic length scale, in the order of 40–50 μm, below which tissue motion is homogeneous. Applied to our data, we illustrate that the method allows for analyses of calcium dynamics in contracting myometrium in unprecedented spatiotemporal detail. Additionally, we use the kinematics of tissue motion to compare calcium signals at the subcellular level and local contractile motion. The computer code used is provided in a freely modifiable form and has potential applicability to in vivo calcium imaging of neural tissue, as well as other smooth muscle tissue.
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Affiliation(s)
- Fiona C Loftus
- Warwick Systems Biology Centre, University of Warwick, Coventry, UK Division of Translational and Systems Medicine, Warwick Medical School, University of Warwick, Coventry, UK Warwick Systems Biology Doctoral Training Centre, University of Warwick, Coventry, UK
| | - Anatoly Shmygol
- Division of Translational and Systems Medicine, Warwick Medical School, University of Warwick, Coventry, UK
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Hyrc KL, Minta A, Escamilla PR, Chan PPL, Meshik XA, Goldberg MP. Synthesis and properties of Asante Calcium Red--a novel family of long excitation wavelength calcium indicators. Cell Calcium 2013; 54:320-33. [PMID: 24017967 DOI: 10.1016/j.ceca.2013.08.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Revised: 07/29/2013] [Accepted: 08/01/2013] [Indexed: 10/26/2022]
Abstract
Although many synthetic calcium indicators are available, a search for compounds with improved characteristics continues. Here, we describe the synthesis and properties of Asante Calcium Red-1 (ACR-1) and its low affinity derivative (ACR-1-LA) created by linking BAPTA to seminaphthofluorescein. The indicators combine a visible light (450-540 nm) excitation with deep-red fluorescence (640 nm). Upon Ca2+ binding, the indicators raise their fluorescence with longer excitation wavelengths producing higher responses. Although the changes occur without any spectral shifts, it is possible to ratio Ca(2+)-dependent (640 nm) and quasi-independent (530 nm) emission when using visible (< 490 nm) or multiphoton (∼780 nm) excitation. Therefore, both probes can be used as single wavelength or, less dynamic, ratiometric indicators. Long indicator emission might allow easy [Ca2+]i measurement in GFP expressing cells. The indicators bind Ca2+ with either high (Kd = 0.49 ± 0.07 μM; ACR-1) or low affinity (Kd = 6.65 ± 0.13 μM; ACR-1-LA). Chelating Zn2+ (Kd = 0.38 ± 0.02 nM) or Mg2+ (Kd∼5mM) slightly raises and binding Co2+ quenches dye fluorescence. New indicators are somewhat pH-sensitive (pKa = 6.31 ± 0.07), but fairly resistant to bleaching. The probes are rather dim, which combined with low AM ester loading efficiency, might complicate in situ imaging. Despite potential drawbacks, ACR-1 and ACR-1-LA are promising new calcium indicators.
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Affiliation(s)
- Krzysztof L Hyrc
- The Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO 63110, USA; Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St. Louis, MO 63110, USA; Alafi Neuroimaging Laboratory, Washington University School of Medicine, St. Louis, MO 63110, USA.
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Abstract
The use of single- and dual-wavelength Ca(2+)-sensitive fluorescent dyes to monitor changes in endothelial and/or smooth muscle intracellular Ca(2+) levels has provided information linking Ca(2+) events to changes in arterial function. Here we describe the in vitro techniques used to selectively load Ca(2+) indicators into either the endothelium or the smooth muscle of cannulated rat cremaster arteries. These vessels normally develop spontaneous myogenic tone that is largely unaffected by the loading of Ca2+ indicators or the subsequent imaging procedures. This suggests that there is minimal Ca2+ buffering or damage, and that the fluorescent indicator-loaded vessels behave similarly to unloaded preparations. Importantly, these approaches are applicable to both isobaric and isometric preparations and have been also used for the study of a number of vascular beds including cerebral, mesenteric, coronary, and skeletal muscle vasculatures.
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Demkow U, Winklewski P, Ciepiela O, Popko K, Lipińska A, Kucharska A, Michalska B, Wąsik M. Modulatory effect of insulin on T cell receptor mediated calcium signaling is blunted in long lasting type 1 diabetes mellitus. Pharmacol Rep 2012; 64:150-6. [PMID: 22580531 DOI: 10.1016/s1734-1140(12)70741-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2011] [Revised: 09/29/2011] [Indexed: 01/12/2023]
Abstract
Insulin significantly influences Ca(2+) signals evoked by various stimulants. In type 1 recent onset diabetes mellitus the proliferative response of T cells is significantly decreased. The number of clinical trials exploring the role of anti-CD3 monoclonal antibodies (mAb) as a therapeutic agent in recent onset diabetes mellitus type 1 is increasing last years. Therefore, a better understanding of the interplay between T cell receptor (TCR) dependent Ca(2+) increase, and insulin is of vital clinical significance. The aim of the study was to assess the effect of insulin on TCR evoked Ca(2+) responses in T lymphocytes obtained from healthy volunteers and patients suffering from long lasting diabetes mellitus type 1. Analysis was performed with use of the flow cytometer. We demonstrated that T cells ability to mobilize Ca(2+) was significantly reduced in long lasting diabetes mellitus type 1. Ca(2+) decrease achieved by the long term incubation with anti-CD3 mAb in T cells from healthy volunteers was restored by insulin. Strong interrelationship between baseline Ca(2+) level and plateau phase response to TCR stimulation was observed in the cytoplasm of cells pre-incubated with insulin from both healthy subjects and diabetic patients (r = 0.95, p < 0.0001 and r = 0.94, p < 0.0001, respectively). We postulate the existence of the interplay between TCR mediated activation and insulin. The TCR-insulin interplay is blunted in long lasting diabetes mellitus type 1. These observations may have an important implication for future therapeutic options in diabetes.
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Affiliation(s)
- Urszula Demkow
- Department of Laboratory Diagnostics and Clinical Immunology of Developmental Age, Medical University of Warsaw, Marszałkowska 24, PL 00-576 Warszawa, Poland.
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Wu S, Hyrc KL, Moulder KL, Lin Y, Warmke T, Snider BJ. Cellular calcium deficiency plays a role in neuronal death caused by proteasome inhibitors. J Neurochem 2009; 109:1225-36. [PMID: 19476541 DOI: 10.1111/j.1471-4159.2009.06037.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cytosolic Ca(2+) concentration ([Ca(2+)](i)) is reduced in cultured neurons undergoing neuronal death caused by inhibitors of the ubiquitin proteasome system. Activation of calcium entry via voltage-gated Ca(2+) channels restores cytosolic Ca(2+) levels and reduces this neuronal death (Snider et al. 2002). We now show that this reduction in [Ca(2+)](i) is transient and occurs early in the cell death process, before activation of caspase 3. Agents that increase Ca(2+) influx such as activation of voltage-gated Ca(2+) channels or stimulation of Ca(2+) entry via the plasma membrane Na-Ca exchanger attenuate neuronal death only if applied early in the cell death process. Cultures treated with proteasome inhibitors had reduced current density for voltage-gated Ca(2+) channels and a less robust increase in [Ca(2+)](i) after depolarization. Levels of endoplasmic reticulum Ca(2+) were reduced and capacitative Ca(2+) entry was impaired early in the cell death process. Mitochondrial Ca(2+) was slightly increased. Preventing the transfer of Ca(2+) from mitochondria to cytosol increased neuronal vulnerability to this death while blockade of mitochondrial Ca(2+) uptake via the uniporter had no effect. Programmed cell death induced by proteasome inhibition may be caused in part by an early reduction in cytosolic and endoplasmic reticulum Ca(2+,) possibly mediated by dysfunction of voltage-gated Ca(2+) channels. These findings may have implications for the treatment of disorders associated with protein misfolding in which proteasome impairment and programmed cell death may occur.
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Affiliation(s)
- Shengzhou Wu
- Laboratory of B. Joy Snider, Hope Center for Neurological Disorders, Saint Louis, Missouri 63110, USA
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Deng B, Zhu P, Wang Y, Feng J, Li X, Xu X, Lu H, Xu Q. Determination of Free Calcium and Calcium-Containing Species in Human Plasma by Capillary Electrophoresis-Inductively Coupled Plasma Optical Emission Spectrometry. Anal Chem 2008; 80:5721-6. [DOI: 10.1021/ac800715c] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Biyang Deng
- College of Chemistry and Chemical Engineering, Guangxi Normal University, Guilin 541004, China, and Department of Material and Chemical Engineering, Guilin University of Technology, Guilin 541004, China
| | - Pingchuan Zhu
- College of Chemistry and Chemical Engineering, Guangxi Normal University, Guilin 541004, China, and Department of Material and Chemical Engineering, Guilin University of Technology, Guilin 541004, China
| | - Yingzi Wang
- College of Chemistry and Chemical Engineering, Guangxi Normal University, Guilin 541004, China, and Department of Material and Chemical Engineering, Guilin University of Technology, Guilin 541004, China
| | - Jinrong Feng
- College of Chemistry and Chemical Engineering, Guangxi Normal University, Guilin 541004, China, and Department of Material and Chemical Engineering, Guilin University of Technology, Guilin 541004, China
| | - Xianfeng Li
- College of Chemistry and Chemical Engineering, Guangxi Normal University, Guilin 541004, China, and Department of Material and Chemical Engineering, Guilin University of Technology, Guilin 541004, China
| | - Xiangshu Xu
- College of Chemistry and Chemical Engineering, Guangxi Normal University, Guilin 541004, China, and Department of Material and Chemical Engineering, Guilin University of Technology, Guilin 541004, China
| | - Hua Lu
- College of Chemistry and Chemical Engineering, Guangxi Normal University, Guilin 541004, China, and Department of Material and Chemical Engineering, Guilin University of Technology, Guilin 541004, China
| | - Qiumei Xu
- College of Chemistry and Chemical Engineering, Guangxi Normal University, Guilin 541004, China, and Department of Material and Chemical Engineering, Guilin University of Technology, Guilin 541004, China
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