scholarly journals The role of calcium ions in the process of acetyltransferase activation during the formation of platelet-activating factor (PAF-acether)

1984 ◽  
Vol 219 (2) ◽  
pp. 419-424 ◽  
Author(s):  
J Gómez-Cambronero ◽  
P Iñarrea ◽  
F Alonso ◽  
M Sánchez Crespo
Keyword(s):  
Intracellular Calcium ◽  
Significant Role ◽  
Calcium Ions ◽  
Calcium Transport ◽  
Platelet Activating Factor ◽  
Peritoneal Macrophages ◽  
Threshold Concentration ◽  
Ionophore A23187 ◽  
Different Doses

The role of Ca2+ in the activation of the enzyme lyso-(platelet-activating factor): acetyl-CoA acetyltransferase was studied in rat peritoneal macrophages in response to complement-coated zymosan particles and ionophore A23187. By using Ca2+-containing buffers, a threshold concentration of extracellular Ca2+ above 1 microM was found to be necessary to observe the activation of the enzyme in response to zymosan. By contrast, a significant role of intracellular Ca2+ in this process could be ruled out, since the putative intracellular calcium-transport antagonist TMB-8 [8-(NN-diethylamino)octyl-3,4,5-trimethoxybenzoate] did not inhibit the activation of the acetyltransferase induced by zymosan in the presence of extracellular Ca+. The link between acetyltransferase activation and extracellular Ca2+ transport was studied by measuring Ca2+ uptake in response to the stimuli. Zymosan particles induced a rapid increment in cell-associated Ca2+ which correlated well with the extent of acetyltransferase activation (r = 0.91) and with the release of platelet-activating factor (r = 0.95) in response to different doses of zymosan. Cellular Ca2+ efflux in response to zymosan particles was also measured and found to be increased, as compared with controls, when the activation of the acetyltransferase declined. In short, the data suggest that the entry of extracellular Ca2+ into the cell is a crucial event in the activation of acetyltransferase and, thereby, in the formation of platelet-activating factor in rat peritoneal macrophages.

Intracellular Calcium Ions Modulate Permeability of the Peritoneal Mesothelium In Vitro

1985 ◽  
Vol 5 (2) ◽  
pp. 105-108 ◽  
Author(s):  
Andrzej Breborowicz ◽  
Jan Knapowski ◽  
Grzegorz Breborowicz
Keyword(s):  
Epithelial Cells ◽  
Intracellular Calcium ◽  
Local Anesthetic ◽  
Calcium Ions ◽  
Calcium Transport ◽  
Calcium Ionophore ◽  
Ionophore A23187 ◽  
Peritoneal Mesothelium ◽  
Vitro Effect

The authors studied the in vitro effect of a calcium-channel-blocker -verapamil, local anesthetic -bupivacaine and a calcium ionophore -A23187 on the permeability of the monolayer mesothelium from the rabbit's mesentery. Verapamil and bupivacaine increased transmesothelial flux of calcium while A23187 increased calcium transport only transiently. Verapamil augmented the permeability of the mesothelium to inulin and urea. However A23187 decreased the transmesothelial flux of inulin only whereas it increased the transport of urea. From this study we have concluded, that intracellular calcium may determine the permeability of the peritoneal mesothelium. Various important biological processes like muscle contraction, secretion of transmitters and hormones, and control of epithelial permability seem to be dependent on intracellular calcium-ion activity (1–4). Our previous paper suggested that a local anesthetic, bupivacaine, produces its effect on the peritoneal mesothelium through interaction with the cytoskeleton of the epithelial cells, and with the mem brane's calcium transport (5). In addition Palant et al found that the permeability of another leaky epithelium, that from the Necturus gallbladder, depends on the extracellular calcium concentrations and may be altered by drugs, which interfere with the entrance of these ions into the epithelial cells (6). Therefore, we decided to study the role that calcium ions may play in the transport of solutes across the peritoneal mesothelium in vitro.

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.

Role of intracellular calcium ions and reactive oxygen species in apoptosis induced by ultrasound

2004 ◽  
Vol 30 (5) ◽  
pp. 683-692 ◽  
Author(s):  
Hidemi Honda ◽  
Takashi Kondo ◽  
Qing-Li Zhao ◽  
Loreto B Feril ◽  
Hiroshi Kitagawa
Keyword(s):  
Reactive Oxygen Species ◽  
Intracellular Calcium ◽  
Calcium Ions ◽  
Reactive Oxygen ◽  
Oxygen Species

scholarly journals Essential Role of Platelet-Activating Factor in Control of Leishmania (Leishmania)amazonensis Infection

2000 ◽  
Vol 68 (11) ◽  
pp. 6355-6361 ◽  
Author(s):  
Maria Valdrinez Campana Lonardoni ◽  
Momtchillo Russo ◽  
Sonia Jancar
Keyword(s):  
Lymph Nodes ◽  
Platelet Activating Factor ◽  
Parasite Load ◽  
Peritoneal Macrophages ◽  
Leishmania Infection ◽  
Prostaglandin E ◽  
No Production ◽  
Regional Lymph Nodes

ABSTRACT In the present study we investigated the role of platelet-activating factor (PAF) and prostaglandins in experimental Leishmania (Leishmania)amazonensis infection and the relationship between these mediators and nitric oxide (NO) production. Mouse peritoneal macrophages elicited with thioglicolate were infected with leishmania amastigotes, and the infection index determined 48 h later. The course of infection was monitored for 5 weeks in mice infected in the footpad with promastigotes by measuring the footpad swelling and parasite load in regional lymph nodes and spleen. The addition of PAF to C57BL/6 mouse macrophages significantly inhibited parasite growth and induced NO production. Treatment of macrophages with a selective PAF antagonist, WEB2086, increased the infection, indicating that endogenously produced PAF regulates macrophage ability to control leishmania infection. This effect of PAF was abolished by addition of the inhibitor of NO synthesis, L-NAME, to the cultures. The addition of prostaglandin E2 significantly increased the infection and NO production. Treatment with cyclo-oxygenase inhibitor, indomethacin, reduced the infection and PAF-induced release of NO. Thus, the increased NO production induced by PAF seems to be mediated by prostaglandins. The more-selective inhibitors of cyclo-oxygenase 2, nimesulide and NS-398, had no significant effect. Thus, antileishmanial activity correlates better with the presence of PAF or absence of prostaglandins than with NO production. In vivo treatment with PAF antagonists significantly increased leishmania lesions, as well as the parasite load, in regional lymph nodes and spleens. These findings indicate that PAF is essential for the control of leishmania infection.

scholarly journals Phosphorylation-dependent and -independent pathways of platelet aggregation

1989 ◽  
Vol 258 (2) ◽  
pp. 479-485 ◽  
Author(s):  
S P Watson ◽  
S Hambleton
Keyword(s):  
Protein Phosphorylation ◽  
Platelet Activating Factor ◽  
Specific Inhibitor ◽  
Human Platelets ◽  
Signalling Pathways ◽  
Ionophore A23187 ◽  
Phorbol Dibutyrate ◽  
Kinase C ◽  
Dependent Pathway

We have used the non-specific inhibitor of protein kinases, staurosporine, to investigate the role of protein phosphorylation during aggregation, the mobilization of intracellular Ca2+ (Ca2+)i and intracellular pH (pHi) in thrombin-stimulated platelets. The concentration of staurosporine chosen for these studies, 1 microM, was previously reported to inhibit protein phosphorylation completely but to have no effect on the activation of phospholipase C in thrombin-stimulated human platelets [Watson, McNally, Shipman & Godfrey (1988) Biochem. J. 249, 345-350]. Aggregation induced by phorbol dibutyrate is slow (several minutes) and is inhibited completely by staurosporine. In contrast, aggregation induced by thrombin, platelet-activating factor or ionophore A23187 is rapid (occurs within 60 s), and is slowed, but not inhibited, in the presence of staurosporine. On the other hand, staurosporine causes a small potentiation of the peak [Ca2+]i signal induced by thrombin and a marked increase in the half-life of decay of this signal, but has no effect on pHi. Under conditions designed to prevent an increase in [Ca2+]i (presence of Ni2+ to prevent Ca2+ entry, and depletion of the intracellular Ca2+ stores), aggregation induced by thrombin resembles that by phorbol dibutyrate and is now inhibited completely by staurosporine. Taken together, these results provide evidence for two signalling pathways for aggregation, a relatively rapid phosphorylation-independent route mediated by Ca2+ and a slower, phosphorylation-dependent, pathway mediated by protein kinase C. Since staurosporine slows aggregation induced by thrombin, it appears that under normal conditions these pathways interact synergistically.

scholarly journals Signaling in TRPV1-induced platelet activating factor (PAF) in human esophageal epithelial cells

2010 ◽  
Vol 298 (2) ◽  
pp. G233-G240 ◽  
Author(s):  
Jie Ma ◽  
Karen M. Harnett ◽  
Jose Behar ◽  
Piero Biancani ◽  
Weibiao Cao
Keyword(s):  
Epithelial Cells ◽  
Western Blot ◽  
Transient Receptor Potential ◽  
Platelet Activating Factor ◽  
Calcium Ionophore ◽  
Transferase Activity ◽  
Ionophore A23187 ◽  
Acetyl Coa ◽  
Coa Transferase

Transient receptor potential channel, vanilloid subfamily member 1 (TRPV1) receptors were identified in human esophageal squamous epithelial cell line HET-1A by RT-PCR and by Western blot. In fura-2 AM-loaded cells, the TRPV1 agonist capsaicin caused a fourfold cytosolic calcium increase, supporting a role of TRPV1 as a capsaicin-activated cation channel. Capsaicin increased production of platelet activating factor (PAF), an important inflammatory mediator that acts as a chemoattractant and activator of immune cells. The increase was reduced by the p38 MAP kinase (p38) inhibitor SB203580, by the cytosolic phospholipase A2 (cPLA2) inhibitor AACOCF3, and by the lyso-PAF acetyltransferase inhibitor sanguinarin, indicating that capsaicin-induced PAF production may be mediated by activation of cPLA2, p38, and lyso-PAF acetyltransferase. To establish a sequential signaling pathway, we examined the phosphorylation of p38 and cPLA2 by Western blot. Capsaicin induced phosphorylation of p38 and cPLA2. Capsaicin-induced p38 phosphorylation was not affected by AACOCF3. Conversely, capsaicin-induced cPLA2 phosphorylation was blocked by SB203580, indicating that capsaicin-induced PAF production depends on sequential activation of p38 and cPLA2. To investigate how p38 phosphorylation may result from TRPV1-mediated calcium influx, we examined a possible role of calmodulin kinase (CaM-K). p38 phosphorylation was stimulated by the calcium ionophore A23187 and by capsaicin, and the response to both agonists was reduced by a CaM inhibitor and by CaM-KII inhibitors, indicating that calcium induced activation of CaM and CaM-KII results in P38 phosphorylation. Acetyl-CoA transferase activity increased in response to capsaicin and was inhibited by SB203580, indicating that p38 phosphorylation in turn causes activation of acetyl-CoA transferase to produce PAF. Thus epithelial cells produce PAF in response to TRPV1-mediated calcium elevation.

The alteration of mitotic events by ionophore A23187 and carbonyl cyanide n-chlorophenylhydrazone

1985 ◽  
Vol 75 (1) ◽  
pp. 347-355
Author(s):  
M.L. Ziegler ◽  
J.E. Sisken ◽  
S. Vedbrat
Keyword(s):  
Oxidative Phosphorylation ◽  
Intracellular Calcium ◽  
Calcium Ions ◽  
Hela Cells ◽  
Cytosolic Calcium ◽  
Ionophore A23187 ◽  
Chromosome Movement ◽  
Low Concentrations ◽  
Carbonyl Cyanide ◽  
Stimulation Of

A large quantity of published work indicates that calcium ions may be involved in the regulation of mitotic events and recent reports suggest that the onset of chromosome movement is dependent upon a transient increase in free cytosolic calcium ions. In this paper we examine the effects of two agents known to perturb intracellular calcium pools on mitosis in HeLa cells. These were the calcium-selective ionophore A23187 and carbonyl cyanide n-chlorophenylhydrazone (CCCP), which is a protonophoric inhibitor of oxidative phosphorylation. Owing to a stimulation of glycolysis, the latter agent does not decrease intracellular ATP in HeLa but does cause mitochondria to release calcium ions. Our data show that, at low concentrations, both agents prolong metaphase but differ in their effects on anaphase and cytokinesis. Studies with chlorotetracycline, a commonly used probe for membrane-associated calcium, verify that these agents do affect calcium pools under the conditions of our experiments. The data presented are consistent with the idea that increased cytosolic calcium levels can directly or indirectly affect mitotic events but, contrary to other suggestions, cause a prolongation of metaphase, i.e. they delay the onset of chromosome movement.

scholarly journals Role of Sodium/Calcium Exchangers in Tumors

Biomolecules ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1257
Author(s):  
Barbora Chovancova ◽  
Veronika Liskova ◽  
Petr Babula ◽  
Olga Krizanova
Keyword(s):  
Cancer Cells ◽  
Calcium Ions ◽  
Calcium Transport ◽  
Current Knowledge ◽  
Transport Systems ◽  
Sodium Ions ◽  
Sodium Calcium Exchanger ◽  
Reverse Mode ◽  
Sodium Calcium

The sodium/calcium exchanger (NCX) is a unique calcium transport system, generally transporting calcium ions out of the cell in exchange for sodium ions. Nevertheless, under special conditions this transporter can also work in a reverse mode, in which direction of the ion transport is inverted—calcium ions are transported inside the cell and sodium ions are transported out of the cell. To date, three isoforms of the NCX have been identified and characterized in humans. Majority of information about the NCX function comes from isoform 1 (NCX1). Although knowledge about NCX function has evolved rapidly in recent years, little is known about these transport systems in cancer cells. This review aims to summarize current knowledge about NCX functions in individual types of cancer cells.

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