Lanthanum increases the rat thymocyte cytoplasmic free calcium concentration by enhancing calcium influx

1986 ◽  
Vol 886 (2) ◽  
pp. 267-271 ◽  
Author(s):  
Joseph Segal
Keyword(s):  
Calcium Concentration ◽  
Calcium Influx ◽  
Free Calcium ◽  
Free Calcium Concentration ◽  
Cytoplasmic Free Calcium

Cytoplasmic free calcium concentration in porcine platelets

1984 ◽  
Vol 800 (2) ◽  
pp. 178-187 ◽  
Author(s):  
A. David Purdon ◽  
James L. Daniel ◽  
Gwendolyn J. Stewart ◽  
Holm Holmsen
Keyword(s):  
Calcium Concentration ◽  
Free Calcium ◽  
Free Calcium Concentration ◽  
Cytoplasmic Free Calcium

The Effects of Chloride Channel Blockers on Platelet Cytoplasmic Free Calcium Concentration and Platelet Aggregation.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 3879-3879
Author(s):  
Songmei Yin ◽  
Xiaolin Chen ◽  
Danian Nie ◽  
Shuangfeng Xie ◽  
Liping Ma ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Calcium Channel ◽  
Calcium Channel Blockers ◽  
Chloride Channel ◽  
Calcium Concentration ◽  
Disulfonic Acid ◽  
Free Calcium ◽  
Channel Blockers ◽  
Free Calcium Concentration ◽  
Cytoplasmic Free Calcium

Abstract Objective To explore the effects of chloride channels on the regulations of platelet cytoplasmic free calcium concentration ([Ca2+]i) and platelet aggregation (PAG). Methods Platelet were separated freshly and then activated by thrombin; The chloride channel blockers 4,4′-diisothiocyano-2, 2′-disulfonic acid stilbene (DIDS) or niflumic acid (NFA), and calcium channel blockers 1-{β-[3-(4-methoxyphenyl)propoxy]- 4-methoxyphenethyl}- 1H - imidazole hydrochloride (SK&F96365) or Nifedipine were added to react with the activated platelets. The effects of each agent on platelet [Ca2+]i and PAG were detected. The combine effects and the interactions among chloride channel blockers (DIDS, NFA) and calcium channel blockers (SK&F96365, Nifedipine) were also investigated. Results Both DIDS and NFA [the concentration were12.5, 25, 50, 100 and 200μmol•L−1 respectively] could inhibit the PAG induced by thrombin (1U/ml) and the effect was dose-dependent. Compared with the control, they had no significant effects on resting [Ca2+]i. Compare with the control group, DIDS (100μmol•L−1), SK&F96365 (100μmol•L−1) and Nifedipine (100μmol•L−1) could significantly reduce the PAG, Ca2+ release and Ca2+ influx activated by thrombin in platelet (P<0.05). DIDS (100μmol•L−1) and SK&F96365 (100μmol•L−1) could enhance each other’s effect on reducing the PAG, Ca2+ release and Ca2+ influx (P<0.05). DIDS (100μmol•L−1) and Nifedipine (100μmol•L−1) could enhance each other’s effect on reducing Ca2+ release (P<0.05). NFA (100μmol•L−1) and SK&F96365 (100μmol•L−1) could weaken each other’s effect on Ca2+ release (P<0.05). NFA (100μmol•L−1) and Nifedipine (100μmol•L−1) could weaken each other’s effect on PAG, Ca2+ release and Ca2+ influx activated by thrombin in platelet (P<0.05). Conclusion The chloride channel blockers DIDS and NFA have no effect on the resting [Ca2+]i and the leak calcium influx of platelet. DIDS can inhibit the Ca2+ release, Ca2+ influx and PAG of platelet induced by thrombin, while NFA can only inhibit the Ca2+ release of platelet induced by thrombin. There are interactions between chloride channel blockers and calcium channel blockers in resting [Ca2+]i and PAG of platelet. The opening of chloride channel can influence the cellular calcium movement of platelet.

Oscillation of cytoplasmic free calcium concentration induced by insulin-like growth factor I

1992 ◽  
Vol 262 (3) ◽  
pp. E307-E311
Author(s):  
I. Kojima ◽  
H. Mogami ◽  
E. Ogata
Keyword(s):  
Growth Factor ◽  
Calcium Concentration ◽  
Calcium Entry ◽  
Free Calcium ◽  
Insulin Like Growth Factor ◽  
Factor I ◽  
Igf I ◽  
Free Calcium Concentration ◽  
Growth Factor I ◽  
Cytoplasmic Free Calcium

The effect of insulin-like growth factor I (IGF-I) on cytoplasmic free calcium concentration ([Ca2+]c) was studied in single BALB/c 3T3 cells by monitoring fura-2 fluorescence. In primed competent cells, IGF-I (1 nM) increased [Ca2+]c in approximately 60% of the cells tested. IGF-I-mediated elevation of [Ca2+]c was observed after a 4- to 17-min lag period. Elevation of [Ca2+]c was only transient but was followed by repetitive increases in [Ca2+]c. The interval between each peak was quite constant in each cell at a given concentration of IGF-I. When the concentration of IGF-I was reduced, both the latent period and interval of each peak were prolonged, whereas amplitude of the increase in [Ca2+]c was not altered. In medium containing 10 microM extracellular calcium, IGF-I did not cause any increase in [Ca2+]c. Likewise, blockade of IGF-induced calcium entry by either cobalt or tetramethrin abolished IGF-I action on [Ca2+]c. IGF-I-mediated oscillation was not affected by either ryanodine or caffeine, compounds that affect calcium-induced calcium release. In addition, pretreatment of the cell with neomycin did not affect IGF-I-mediated oscillation. In agreement with this, IGF-I did not augment production of [3H]inositol trisphosphate in cells prelabeled with [3H]inositol. These results indicate that IGF-I induces oscillation of [Ca2+]c in a single primed competent cell and that the oscillation is totally dependent on IGF-I-mediated calcium entry.

Effect of secretagogues on cytoplasmic free calcium in alveolar type II epithelial cells

1987 ◽  
Vol 253 (5) ◽  
pp. C679-C686 ◽  
Author(s):  
K. Sano ◽  
D. R. Voelker ◽  
R. J. Mason
Keyword(s):  
Pulmonary Surfactant ◽  
Calcium Concentration ◽  
Free Calcium ◽  
Alveolar Type ◽  
Type Ii Cells ◽  
Type Ii ◽  
Alveolar Type Ii Cells ◽  
Surfactant Secretion ◽  
Free Calcium Concentration ◽  
Cytoplasmic Free Calcium

Pulmonary surfactant is synthesized and secreted by alveolar type II epithelial cells. Although intracellular calcium and other second messengers have been implicated in secretion by type II cells, this is the first report on measurement of cytoplasmic free calcium concentration ([Ca2+]i). Known secretagogues, 12-O-tetradecanoylphorbol-13-acetate (TPA) and terbutaline, were tested to see if they caused rapid increases in cytoplasmic calcium. Ionomycin, a calcium ionophore, was used to increase cytoplasmic free calcium concentration, to determine if a rapid increase in cytoplasmic free calcium would stimulate secretion, and to measure interactions with other secretagogues. Ionomycin increased both [Ca2+]i and pulmonary surfactant secretion from alveolar type II cells. A low concentration of ionomycin (100 nM) greatly enhanced secretion stimulated by terbutaline or by 8-bromo-cAMP but only had an additive effect on secretion stimulated by TPA. Terbutaline transiently increased [Ca2+]i by 24% over control basal condition, and the increase in [Ca2+]i produced by terbutaline occurred in the absence of extracellular calcium. TPA itself did not change [Ca2+]i. However, TPA completely inhibited the terbutaline-induced increase of [Ca2+]i but not the increase due to ionomycin. When alveolar type II cells were loaded with 2-(2-bis-[carboxymethyl]-amino-5-methyl-phenoxy)-methyl-6-methoxy-8-bis carboxymethylaminoquinoline (quin2) in calcium-free buffer, [Ca2+]i decreased from 143 +/- 10 to 31 +/- 8 nM. Lowering [Ca2+]i inhibited TPA- or terbutaline-induced secretion by 22 and 40%, respectively. Although the precise role of cytoplasmic free calcium on surfactant secretion cannot be established on the basis of current data, our results indicate that an increase in cytoplasmic free calcium produced by ionomycin stimulates secretion and that an increase in [Ca2+]i affects cAMP-induced secretion more than protein kinase C-mediated secretion in alveolar type II cells.

66 Orai1 IS REQUIRED TO MAINTAIN CALCIUM OSCILLATION AT FERTILIZATION IN PORCINE OOCYTES

2012 ◽  
Vol 24 (1) ◽  
pp. 145
Author(s):  
C. Wang ◽  
K. Lee
Keyword(s):  
Plasma Membrane ◽  
Embryo Development ◽  
Calcium Concentration ◽  
Calcium Influx ◽  
Calcium Entry ◽  
Intracellular Free Calcium ◽  
Calcium Oscillation ◽  
Free Calcium ◽  
Intracellular Free Calcium Concentration ◽  
Free Calcium Concentration

During mammalian fertilization, the sperm induces an oscillation in the oocyte's intracellular free calcium concentration that stimulates oocyte activation. The train of calcium spikes is maintained by an influx of calcium across the plasma membrane, probably through a mechanism known as store-operated calcium entry. Despite their importance, little is known about the identity and regulation of the calcium entry channels that mediate calcium influx at fertilization. Previously we have shown that the Orai1 protein is localised in the plasma membrane of pig oocytes and plays an important role in calcium entry after depletion of the intracellular calcium stores. In this study, we investigated the function of Orai1 in signal transduction during fertilization. In Experiment 1, Orai1 levels were down-regulated by injecting immature pig oocytes with small interfering RNA (siRNA) against Orai1; control cells were injected with scrambled siRNA. The injected oocytes were then matured in vitro for 44 h. In Experiment 2, Orai1 was overexpressed by microinjection of mRNA encoding Orai1 conjugated to the enhanced green fluorescent protein (EGFP-Orai1) 36 h after the beginning of maturation; these oocytes were incubated for an additional 8 h. At the end of the incubation period the oocytes were loaded with the calcium indicator dye fura-2 and inseminated. Changes in the intracellular free calcium concentration were monitored by means of a fluorescence imaging system. Some of the fertilized oocytes were cultured for 7 days, at which time embryo development together with the total nuclear number of the embryos were recorded. Data were subjected to 1-way ANOVA; differences between treatments were analysed using the Tukey test. The level of Orai1 protein was significantly lower in Orai1 siRNA-injected oocytes compared to the control group, as determined by Western blot, indicating successful down-regulation of Orai1. During fertilization, control oocytes displayed a series of calcium transients that lasted up to 8 h. However, in Orai1 siRNA-injected oocytes (9 out of 10 measured) only 1 calcium rise could be observed; these oocytes were unable to generate repetitive calcium signals after gamete fusion. Overexpression of Orai1 also disrupted the pattern of the normal fertilization calcium signal; the oscillation ceased after just a few Ca2+ rises in 8 out of 10 oocytes. The percentage of cleaved oocytes was lower in the siRNA-injected group compared to both non-injected or control siRNA-injected oocytes (38.4 ± 4.6% vs 70.5 ± 2.8% and 70.4 ± 2.4%; P < 0.05). The frequency of blastocyst (1.9 ± 0.8% vs11.0 ± 3.1% and 9.9 ± 1.4%) and the total cell number per blastocyst (19.8 ± 0.8 vs 36.2 ± 0.7 and 33.5 ± 5.5) was also significantly lower in oocytes with down-regulated Orai1 levels. These results indicate that an Orai1-mediated calcium influx is required to maintain proper calcium oscillation at fertilization and is also essential to support subsequent embryo development.

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