Cell viability modulation through changes of Ca2+-dependent signalling pathways (original) (raw)
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IEEE Transactions on Biomedical Engineering, 2019
Goal: Herein, the variations in transient Ca 2+ mobilizations in HeLa cells exposed to a single, non-thermal pulsed electric field (PEF) are described. Methods: Three PEF waveforms categorized by pulse duration and intensity were used to deduce the kinetics involved in Ca 2+ mobilization. A fast microscopic fluorescent imaging system and fluorescent molecular probe were used to observe transient intracellular Ca 2+ mobilization after pulse exposure. The sources and pathways in the transient Ca 2+ mobilizations were investigated using an inhibitor of inositol-1,4,5trisphosphate receptor (IP3R) on the endoplasmic reticulum (ER) along with a Ca 2+-free buffer. Results: When exposed to the 10-μslong PEF, the Ca 2+ concentration increased mainly at the cathodic region near the membrane. However, Ca 2+ concentration increased at both anodic and cathodic regions when Na + concentration in the buffer was reduced. Ca 2+ concentration increased only in the presence of extracellular Ca 2+. Conclusion: These results suggest that the 10-μs PEF takes a large amount of extracellular Na + into the cell through the electropermeabilized plasma membrane, especially at the anodic side, resulting in the suppression of the Ca 2+ influx. On the contrary, the 20-ns-long PEF increased Ca 2+ concentration in the surrounding region of the nucleus only in the presence of extracellular Ca 2+. The PEF exposure with inhibition of the IP3R indicates that increased Ca 2+ ions are released from the ER via the activated IP3R. Significance: These mechanisms could induce specific cell responses, such as Ca 2+ oscillations, Ca 2+ waves, and Ca 2+ puffs.
Spatial quantification of cytosolic Ca2+ accumulation in nonexcitable cells: An analytical study
IEEE/ACM Transactions on Computational Biology and Bioinformatics, 2000
Calcium ions act as messengers in a broad range of processes such as learning, apoptosis, and muscular movement. The transient profile and the temporal accumulation of calcium signals have been suggested as the two main characteristics in which calcium cues encode messages to be forwarded to downstream pathways. We address the analytical quantification of calcium temporal-accumulation in a long, thin section of a nonexcitable cell by solving a boundary value problem. In these expressions we note that the cytosolic Ca 2þ accumulation is independent of every intracellular calcium flux and depends on the Ca 2þ exchange across the membrane, cytosolic calcium diffusion, geometry of the cell, extracellular calcium perturbation, and initial concentrations. In particular, we analyse the time-integrated response of cytosolic calcium due to i) a localised initial concentration of cytosolic calcium and ii) transient extracellular perturbation of calcium. In these scenarios, we conclude that i) the range of calcium progression is confined to the vicinity of the initial concentration, thereby creating calcium microdomains; and ii) we observe a low-pass filtering effect in the response driven by extracellular Ca 2þ perturbations. Additionally, we note that our methodology can be used to analyse a broader range of stimuli and scenarios.
Intracellular Ca 2+ levels in rat ventricle cells exposed to extremely low frequency magnetic field
Electromagnetic Biology and Medicine, 2011
Objective: Electromagnetic fields can affect intracellular Ca 2þ levels. The aim of this study was to determine the changes intracellular Ca 2þ concentration in cardiac ventricle cells of rats exposed to 0.25 mT (2.5 Gauss) magnetic field. Methods: Forty-five male rats were introduced to this study. The rats were divided into three groups: control, sham, and experiment. The experimental group was exposed to 0.25 mT extremely low frequency (ELF) magnetic field for 14 days, 3 h/day. The sham group was treated like the experimental group, except for elf-magnetic field exposure. The control group was not subjected to anything and differed from the experimental group and sham group. In the end of experiment, rats were sacrificed, cardiac tissue was removed, and these were fixed in 10% neutral formalin. Then, ventricular cells were stained by Alizarin red staining method. Results: In the light microscopic examinations of control groups, in myofibril structures between groups, changes were not observed. In myofibril regions of the experimental group compared to other groups, increased heterogen Ca 2þ accumulations were found. Conclusion: ELF magnetic fields are used in daily life. The results of this study show that intracellular Ca 2þ accumulation in cardiac ventricles can increase in rats exposed to ELF magnetic field.
Primary pathways of intracellular Ca2+ mobilization by nanosecond pulsed electric field
Biochimica et Biophysica Acta (BBA) - Biomembranes, 2013
Permeabilization of cell membranous structures by nanosecond pulsed electric field (nsPEF) triggers transient rise of cytosolic Ca 2+ concentration ([Ca 2+ ] i), which determines multifarious downstream effects. By using fast ratiometric Ca 2+ imaging with Fura-2, we quantified the external Ca 2+ uptake, compared it with Ca 2+ release from the endoplasmic reticulum (ER), and analyzed the interplay of these processes. We utilized CHO cells which lack voltage-gated Ca 2+ channels, so that the nsPEF-induced [Ca 2+ ] i changes could be attributed primarily to electroporation. We found that a single 60-ns pulse caused fast [Ca 2+ ] i increase by Ca 2+ influx from the outside and Ca 2+ efflux from the ER, with the E-field thresholds of about 9 and 19 kV/cm, respectively. Above these thresholds, the amplitude of [Ca 2+ ] i response increased linearly by 8-10 nM per 1 kV/cm until a critical level between 200 and 300 nM of [Ca 2+ ] i was reached. If the critical level was reached, the nsPEF-induced Ca 2+ signal was amplified up to 3000 nM by engaging the physiological mechanism of Ca 2+-induced Ca 2+-release (CICR). The amplification was prevented by depleting Ca 2+ from the ER store with 100 nM thapsigargin, as well as by blocking the ER inositol-1,4,5-trisphosphate receptors (IP 3 R) with 50 μM of 2-aminoethoxydiphenyl borate (2-APB). Mobilization of [Ca 2+ ] i by nsPEF mimicked native Ca 2+ signaling, but without preceding activation of plasma membrane receptors or channels. NsPEF stimulation may serve as a unique method to mobilize [Ca 2+ ] i and activate downstream cascades while bypassing the plasma membrane receptors.
Pflügers Archiv, 1998
Ca 2+ -dependent vesicular fusion was studied in single whole-cell patch-clamped rat basophilic leukemia (RBL) cells using the capacitance technique. Dialysis of the cells with 10 µM free Ca 2+ and 300 µM guanosine 5′-O-(3-thiotriphosphate) (GTP[γ-S]) resulted in prominent capacitance increases. However, dialysis with either Ca 2+ (225 nM to 10 µM) or GTP[γ-S] alone failed to induce a capacitance change. Under conditions of weak Ca 2+ buffering (0.1 mM EGTA), activation of Ca 2+ -release-activated Ca 2+ (CRAC) channels by dialysis with inositol 1,4,5trisphosphate (InsP 3 ) failed to induce a capacitance increase even in the presence of GTP[γ-S]. However, when Ca 2+ ATPases were inhibited by thapsigargin, InsP 3 and GTP[γ-S] led to a pronounced elevation in membrane capacitance. This increase was dependent on a rise in intracellular Ca 2+ because it was abolished when cells were dialysed with a high level of EGTA (10 mM) in the recording pipette. The increase was also dependent on Ca 2+ influx because it was effectively suppressed when external Ca 2+ was removed. Our results demonstrate that I CRAC represents an important source of Ca 2+ for triggering a secretory response.
Bioelectromagnetics, 2009
Calcium is an important molecule in a number of biological systems. Often these systems are signal transduction cascades involving molecules such as ATP. ATP activates second messengers which can interact with ion channels on the endoplasmic/sarcoplasmic reticulum resulting in the emptying of the intracellular calcium stores and an increase in cytosolic free calcium concentration ([Ca 2þ ] c). Changes in [Ca 2þ ] c can be influenced by external factors such as a static magnetic field (SMF). One hypothesis suggests that a SMF affects the cells through the radical pair mechanism. By reducing the number of antioxidant molecules like glutathione (GSH), the proportion of free radicals in the cells is increased and may lead to a greater probability of a biological response to a SMF. The purpose of this study was to determine if the [Ca 2þ ] c response to ATP was affected by depletion of GSH by diethylmaleate (DEM) and the absence or presence of a 100 mT homogeneous SMF. Undifferentiated HL-60 cells were loaded with fura-2 AM. [Ca 2þ ] c was measured in real time using a ratiometric fluorescence spectroscopy system. Various (DEM) ranging from 1 to 15 mM were added to deplete GSH. Cells were either exposed to sham or magnetic field (100 mT) for 13 min (780 s) and challenged with 1 mM ATP. The data show that [Ca 2þ ] c was elevated following treatment with DEM with greater [Ca 2þ ] c at higher [DEM]. The [Ca 2þ ] c response to ATP was decreased as the DEM concentration increased. However, there was no effect of a 100 mT SMF on the average [Ca 2þ ] c peak following ATP activation or the full width at half maximum (FWHM) of the [Ca 2þ ] c response and recovery after ATP activation.