Regulation of intracellular calcium in N1E-115 neuroblastoma cells: the role of Na+/Ca2+exchange

2002 ◽  
Vol 282 (5) ◽  
pp. C1000-C1008 ◽  
Author(s):  
Kara L. Kopper ◽  
Joseph S. Adorante
Keyword(s):  
Membrane Potential ◽  
Intracellular Calcium ◽  
Normal Cell ◽  
Buffer Capacity ◽  
Neuroblastoma Cells ◽  
Fold Increase ◽  
Scorpion Venom ◽  
Reverse Mode ◽  
Intracellular Ca

In fura 2-loaded N1E-115 cells, regulation of intracellular Ca2+ concentration ([Ca2+]i) following a Ca2+ load induced by 1 μM thapsigargin and 10 μM carbonylcyanide p-trifluoromethyoxyphenylhydrazone (FCCP) was Na+ dependent and inhibited by 5 mM Ni2+. In cells with normal intracellular Na+ concentration ([Na+]i), removal of bath Na+, which should result in reversal of Na+/Ca2+exchange, did not increase [Ca2+]i unless cell Ca2+ buffer capacity was reduced. When N1E-115 cells were Na+ loaded using 100 μM veratridine and 4 μg/ml scorpion venom, the rate of the reverse mode of the Na+/Ca2+ exchanger was apparently enhanced, since an ∼4- to 6-fold increase in [Ca2+]ioccurred despite normal cell Ca2+ buffering. In SBFI-loaded cells, we were able to demonstrate forward operation of the Na+/Ca2+ exchanger (net efflux of Ca2+) by observing increases (∼ 6 mM) in [Na+]i. These Ni2+ (5 mM)-inhibited increases in [Na+]i could only be observed when a continuous ionomycin-induced influx of Ca2+ occurred. The voltage-sensitive dye bis-(1,3-diethylthiobarbituric acid) trimethine oxonol was used to measure changes in membrane potential. Ionomycin (1 μM) depolarized N1E-115 cells (∼25 mV). This depolarization was Na+dependent and blocked by 5 mM Ni2+ and 250–500 μM benzamil. These data provide evidence for the presence of an electrogenic Na+/Ca2+ exchanger that is capable of regulating [Ca2+]i after release of Ca2+ from cell stores.

Intracellular calcium levels in the Plasmodium berghei ookinete

Parasitology ◽  
2008 ◽  
Vol 135 (12) ◽  
pp. 1355-1362 ◽  
Author(s):  
I. SIDÉN-KIAMOS ◽  
C. LOUIS
Keyword(s):  
Intracellular Calcium ◽  
Plasmodium Berghei ◽  
Calcium Concentration ◽  
Insect Cells ◽  
Ionophore A23187 ◽  
Rodent Malaria Parasite ◽  
Calcium Indicators ◽  
Intracellular Ca

SUMMARYOokinetes are the motile and invasive stages of Plasmodium parasites in the mosquito host. Here we explore the role of intracellular Ca2+ in ookinete survival and motility as well as in the formation of oocysts in vitro in the rodent malaria parasite Plasmodium berghei. Treatment with the Ca2+ ionophore A23187 induced death of the parasite, an effect that could be prevented if the ookinetes were co-incubated with insect cells before incubation with the ionophore. Treatment with the intracellular calcium chelator BAPTA/AM resulted in increased formation of oocysts in vitro. Calcium imaging in the ookinete using fluorescent calcium indicators revealed that the purified ookinetes have an intracellular calcium concentration in the range of 100 nm. Intracellular calcium levels decreased substantially when the ookinetes were incubated with insect cells and their motility was concomitantly increased. Our results suggest a pleiotropic role for intracellular calcium in the ookinete.

Distinct Intracellular Calcium Profiles Following Influx Through N- Versus L-Type Calcium Channels: Role of Ca2+-Induced Ca2+ Release

2004 ◽  
Vol 92 (1) ◽  
pp. 135-143 ◽  
Author(s):  
Keith Tully ◽  
Steven N. Treistman
Keyword(s):  
Intracellular Calcium ◽  
Ryanodine Receptors ◽  
Decay Rates ◽  
Selective Activation ◽  
Intracellular Ca ◽  
Pheochromocytoma Pc12 ◽  
High Concentrations ◽  
Neuronal Functions ◽  
Temporal Profiles

Selective activation of neuronal functions by Ca2+ is determined by the kinetic profile of the intracellular calcium ([Ca2+]i) signal in addition to its amplitude. Concurrent electrophysiology and ratiometric calcium imaging were used to measure transmembrane Ca2+ current and the resulting rise and decay of [Ca2+]i in differentiated pheochromocytoma (PC12) cells. We show that equal amounts of Ca2+ entering through N-type and L-type voltage-gated Ca2+ channels result in significantly different [Ca2+]i temporal profiles. When the contribution of N-type channels was reduced by ω-conotoxin MVIIA treatment, a faster [Ca2+]i decay was observed. Conversely, when the contribution of L-type channels was reduced by nifedipine treatment, [Ca2+]i decay was slower. Potentiating L-type current with BayK8644, or inactivating N-type channels by shifting the holding potential to −40 mV, both resulted in a more rapid decay of [Ca2+]i. Channel-specific differences in [Ca2+]i decay rates were abolished by depleting intracellular Ca2+ stores with thapsigargin or by blocking ryanodine receptors with ryanodine, suggesting the involvement of Ca2+-induced Ca2+ release (CICR). Further support for involvement of CICR is provided by the demonstration that caffeine slowed [Ca2+]i decay while ryanodine at high concentrations increased the rate of [Ca2+]i decay. We conclude that Ca2+ entering through N-type channels is amplified by ryanodine receptor mediated CICR. Channel-specific activation of CICR provides a mechanism whereby the kinetics of intracellular Ca2+ leaves a fingerprint of the route of entry, potentially encoding the selective activation of a subset of Ca2+-sensitive processes within the neuron.

Na+/Ca2+ exchange and its role in intracellular Ca2+ regulation in guinea pig detrusor smooth muscle

2001 ◽  
Vol 280 (5) ◽  
pp. C1090-C1096 ◽  
Author(s):  
C. Wu ◽  
C. H. Fry
Keyword(s):  
Smooth Muscle ◽  
Membrane Potential ◽  
Guinea Pig ◽  
Outward Current ◽  
Detrusor Smooth Muscle ◽  
Small Rise ◽  
Intracellular Ca ◽  
Net Flux ◽  
Isolated Smooth Muscle Cells

The role of Na+/Ca2+ exchange in regulating intracellular Ca2+ concentration ([Ca2+]i) in isolated smooth muscle cells from the guinea pig urinary bladder was investigated. Incremental reduction of extracellular Na+ concentration resulted in a graded rise of [Ca2+]i; 50–100 μM strophanthidin also increased [Ca2+]i. A small outward current accompanied the rise of [Ca2+]i in low-Na+ solutions (17.1 ± 1.8 pA in 29.4 mM Na+). The quantity of Ca2+ influx through the exchanger was estimated from the charge carried by the outward current and was ∼30 times that which is necessary to account for the rise of [Ca2+]i, after correction was made for intracellular Ca2+ buffering. Ca2+ influx through the exchanger was able to load intracellular Ca2+ stores. It is concluded that the level of resting [Ca2+]i is not determined by the exchanger, and under resting conditions (membrane potential −50 to −60 mV), there is little net flux through the exchanger. However, a small rise of intracellular Na+ concentration would be sufficient to generate significant net Ca2+ influx.

Differential effects of intracellular calcium elevating agents on adrenergic-stimulated cyclic nucleotide and melatonin synthesis in rat pinealocytes

1992 ◽  
Vol 70 (9) ◽  
pp. 1254-1260 ◽  
Author(s):  
Anthony K. Ho ◽  
Joshua Cheng ◽  
Marc Girard
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Cyclic Amp ◽  
Intracellular Calcium ◽  
Cyclic Nucleotide ◽  
Melatonin Synthesis ◽  
Kinase C ◽  
Mechanism Of Inhibition ◽  
Intracellular Ca

In this study, the role of elevation of intracellular Ca2+ and activation of protein kinase C on adrenergic-stimulated cyclic nucleotide accumulation and melatonin synthesis in rat pinealocytes was investigated. It was found that whereas KCl, ionomycin, and ouabain, three Ca2+-elevating agents, had a potentiating effect on adrenergic-stimulated cylic AMP response, their effects on melatonin synthesis were inhibitory. Similar inhibition was also observed when dibutyryl cyclic AMP was used to stimulate melatonin synthesis. By determining intracellular Ca2+ directly, it was found that the enhancing effects of these agents on the cyclic AMP response but not their inhibitory effects on melatonin synthesis paralleled their abilities to elevate intracellular Ca2+. In comparison, activation of protein kinase C significantly enhanced the adrenergic-stimulated cyclic AMP response and, to a lesser degree, the adrenergic-stimulated N-acetyltransferase and melatonin levels. These results indicate that (i) Ca2+-elevating agents have opposite effects on adrenergic-stimulated cyclic AMP and melatonin production; (ii) a post cyclic AMP event of importance to melatonin synthesis is inhibited by these agents; and (iii) the mechanism of inhibition may not be directly related to their effect on intracellular Ca2+.Key words: intracellular calcium, protein kinase C, melatonin, pineal gland.

scholarly journals Oscillatory membrane potential changes in cells of mesenchymal origin: the role of an intracellular calcium regulating system

1979 ◽  
Vol 81 (1) ◽  
pp. 49-61
Author(s):  
P. G. Nelson ◽  
M. P. Henkart
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Potential ◽  
Intracellular Calcium ◽  
Calcium Ion ◽  
Surface Membrane ◽  
Ion Concentration ◽  
Free Calcium ◽  
Potassium Ions ◽  
Calcium Ion Concentration

A number of mesenchymal cells (fibroblasts, macrophages and megakaryocytes) respond to a variety of stimuli with large hyperpolarizations lasting several seconds (the H.A. response). The H.A. responses can occur as repetitive trains or oscillations. These hyperpolarizations are due to an increase of the surface membrane permeability to potassium ions which is probably mediated by an increase in the cytoplasmic free calcium ion concentration. Evidence is discussed which suggests that the source of this increased calcium, is least in part, an intracellular sequestering system, probably the endoplasmic reticulum. A model capable of producing oscillatory changes in membrane potential is proposed based on such an intracellular calcium sequestering and releasing system.

scholarly journals Constitutively active phosphodiesterase activity regulates urinary bladder smooth muscle function: critical role of KCa1.1 channel

2012 ◽  
Vol 303 (9) ◽  
pp. F1300-F1306 ◽  
Author(s):  
Wenkuan Xin ◽  
Qiuping Cheng ◽  
Rupal P. Soder ◽  
Eric S. Rovner ◽  
Georgi V. Petkov
Keyword(s):  
Membrane Potential ◽  
Cell Membrane ◽  
Fold Increase ◽  
Cell Membrane Potential ◽  
Bladder Smooth Muscle ◽  
Channel Current ◽  
Intracellular Ca ◽  
Urinary Bladder Smooth Muscle ◽  
Pharmacological Blockade ◽  
Evoked Contractions

Pharmacological blockade of cyclic nucleotide phosphodiesterase (PDE) can relax human urinary bladder smooth muscle (UBSM); however, the underlying cellular mechanism is unknown. In this study, we investigated the effects of PDE pharmacological blockade on human UBSM excitability, spontaneous and nerve-evoked contractility, and determined the underlying cellular mechanism mediating these effects. Patch-clamp electrophysiological experiments showed that 3-isobutyl-1-methylxanthine (10 μM), a nonselective PDE inhibitor, caused ∼3.6-fold increase in the transient KCa1.1 channel current frequency and ∼2.5-fold increase in the spontaneous transient hyperpolarization frequency in UBSM-isolated cells. PDE blockade also caused ∼5.6-mV hyperpolarization of the UBSM cell membrane potential. Blocking the KCa1.1 channels with paxilline abolished the spontaneous transient hyperpolarization and the hyperpolarization effect of PDE blockade on the UBSM cell membrane potential. Live cell Ca2+-imaging experiments showed that PDE blockade significantly decreased the global intracellular Ca2+ levels. Attenuation of PDE activity significantly reduced spontaneous phasic contraction amplitude, muscle force integral, duration, frequency, and muscle tone of human UBSM isolated strips. Blockade of PDE also significantly reduced the contraction amplitude, muscle force integral, and duration of the nerve-evoked contractions induced by 20-Hz electrical field stimulation. Pharmacological inhibition of KCa1.1 channels abolished the relaxation effects of PDE blockade on both spontaneous and nerve-evoked contractions in human UBSM-isolated strips. Our data provide strong evidence that in human UBSM PDE is constitutively active, thus maintaining spontaneous UBSM contractility. PDE blockade causes relaxation of human UBSM by increasing transient KCa1.1 channel current activity, hyperpolarizing cell membrane potential, and decreasing the global intracellular Ca2+.

scholarly journals Hydrogen Sulfide Regulates the [Ca2+]iLevel in the Primary Medullary Neurons

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Xiaoni Liu ◽  
Nana Zhang ◽  
Yingjiong Ding ◽  
Dongqing Cao ◽  
Ying Huang ◽  
...  
Keyword(s):  
Hydrogen Sulfide ◽  
Intracellular Calcium ◽  
Calcium Influx ◽  
Cultured Neurons ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Reversal Effect ◽  
Intracellular Ca ◽  
Medullary Neurons

In the present study, we attempted to elucidate mechanisms for the regulation of intracellular calcium levels by H2S in primary rat medullary neurons. Our results showed that NaHS significantly increased the level ofCa2+iin rat medullary neurons in a concentration-dependent manner. L-Cysteine and SAM significantly raised the level ofCa2+iin the medullary neurons while HA and/or AOAA produced a reversal effect. In addition, L-cysteine and SAM significantly increased but HA and/or AOAA decreased the production of H2S in the cultured neurons. TheCa2+ielevation induced by H2S was significantly diminished by EGTA-Ca2+-free solutions, and this elevation was also reduced by nifedipine or nimodipine and mibefradil, suggesting the role of L-type and/or T-type Ca2+channels. Moreover, the effect of H2S onCa2+ilevel in neurons was significantly attenuated by BAPTA-AM and thapsigargin, suggesting the source of Ca2+. Therefore, we concluded that both exogenous and endogenous H2S elevatesCa2+ilevel in primarily cultured rat medullary neurons via both increasing calcium influx and mobilizing intracellular Ca2+stores from ER.

Intracellular calcium signals in response to bradykinin in individual neuroblastoma cells

1995 ◽  
Vol 269 (4) ◽  
pp. C841-C848 ◽  
Author(s):  
J. S. Coggan ◽  
S. H. Thompson
Keyword(s):  
Intracellular Calcium ◽  
Neuroblastoma Cells ◽  
Receptor Subtype ◽  
Half Time ◽  
Calcium Signals ◽  
Fura 2 ◽  
Low Concentrations ◽  
Intracellular Ca ◽  
High Concentrations ◽  
20 Nm

The Ca indicator fura 2 was used to study the modulation of cytoplasmic Ca by bradykinin (Bk) in single N1E-115 murine neuroblastoma cells. Increases in cytoplasmic Ca in response to Bk were mediated by the B2 receptor subtype. Responses to high concentrations of Bk (1-100 nM) were homogeneous and characterized by a rapidly rising transient that decayed to baseline in the continued presence of agonist, with a half-time of 15 s. Responses to low concentrations of Bk (100-500 pM) were more heterogeneous, with longer latencies and often with oscillations. Pretreatment with thapsigargin for 20 min prevented the Ca response, showing that the Ca change results from intracellular Ca release. Removal of external Ca had little effect on the response to Bk, indicating that the agonist does not activate Ca influx. The extent of Ca release and refilling after Bk was tested with ionomycin. A saturating dose of Bk (20 nM) mobilizes > 90% of stored Ca within 30 s, and this is replaced slowly. Replacement of external Na by N-methyl-D-glucamine to block Na/Ca exchange affected the Ca response, causing decreases in latency and in the period of Ca oscillations and increases in overall duration and peak amplitude of the response.

Effect of acidosis on tension and [Ca2+]iin rat cerebral arteries: is there a role for membrane potential?

1998 ◽  
Vol 274 (2) ◽  
pp. H655-H662 ◽  
Author(s):  
Hong-Li Peng ◽  
Peter E. Jensen ◽  
Holger Nilsson ◽  
Christian Aalkjær
Keyword(s):  
Smooth Muscle ◽  
Membrane Potential ◽  
Isometric Force ◽  
Cerebral Arteries ◽  
Bathing Solution ◽  
Hypercapnic Acidosis ◽  
Small Arteries ◽  
Intracellular Ca ◽  
Intracellular Microelectrodes

The cellular mechanism responsible for the reduction of tension in cerebral small arteries to acidosis is not known. In this study the role of smooth muscle intracellular Ca2+ concentration ([Ca2+]i) and membrane potential for the relaxation to acidosis was investigated in isolated rat cerebral small arteries. Isometric force was measured simultaneously with [Ca2+]i(fura 2) or with membrane potential (intracellular microelectrodes), and acidosis was induced by increasing[Formula: see text] or reducing[Formula: see text] of the bathing solution. Both hypercapnic and normocapnic acidosis were associated with a reduction of intracellular pH [measured with 2′,7′-bis-(carboxyethyl)-5 (and -6)-carboxyfluorescein], caused relaxation, and reduced [Ca2+]i. However, whereas hypercapnic acidosis caused hyperpolarization, normocapnic acidosis was associated with depolarization. It is concluded that a reduction of [Ca2+]iis in part responsible for the direct effect of the acidosis on the vascular smooth muscle both during normo- and hypercapnia. The mechanism responsible for the reduction of [Ca2+]idiffers between the hypercapnic and normocapnic acidosis, being partly explained by hyperpolarization during hypercapnic acidosis, whereas it is seen despite depolarization during normocapnic acidosis.

Role of Membrane Potential in Calcium Signaling During Rhythmic Bursting in Tritonia Swim Interneurons

2007 ◽  
Vol 97 (3) ◽  
pp. 2204-2214 ◽  
Author(s):  
Evan S. Hill ◽  
Paul S. Katz
Keyword(s):  
Membrane Potential ◽  
Action Potentials ◽  
Laser Scanning ◽  
Time Course ◽  
Motor Pattern ◽  
Confocal Laser Scanning Microscope ◽  
Confocal Laser ◽  
Intracellular Ca ◽  
Potential Waveform

Rhythmic bursting in neurons is accompanied by dynamic changes in intracellular Ca2+ concentration. These Ca2+ signals may be caused by membrane potential changes during bursting and/or by synaptic inputs. We determined that membrane potential is responsible for most, if not all, of the cytoplasmic Ca2+ signal recorded during rhythmic bursting in two neurons of the escape swim central pattern generator (CPG) of the mollusk, Tritonia diomedea: ventral swim interneuron B (VSI) and cerebral neuron 2 (C2). Ca2+ signals were imaged with a confocal laser scanning microscope while the membrane potential was recorded at the soma. During the swim motor pattern (SMP), Ca2+ signals in both neurons transiently increased during each burst of action potentials with a more rapid decay in secondary than in primary neurites. VSI and C2 were then voltage-clamped at the soma, and each neuron's own membrane potential waveform recorded during the SMP was played back as the voltage command. In all regions of VSI, this completely reproduced the amplitude and time course of Ca2+ signals observed during the SMP, but in C2, the amplitude was lower in the playback experiments than during the SMP, possibly due to space clamp problems. Therefore in VSI, the cytoplasmic Ca2+ signal during the SMP can be accounted for by its membrane potential excursions, whereas in C2 the membrane potential excursions can account for most of the SMP Ca2+ signal.

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