scholarly journals Activation of (arachidonyl) phosphatidylinositol turnover in rabbit neutrophils by the calcium ionophore A23187

1981 ◽  
Vol 194 (2) ◽  
pp. 497-505 ◽  
Author(s):  
R P Rubin ◽  
L E Sink ◽  
R J Freer
Keyword(s):  
Arachidonic Acid ◽  
Maximum Rate ◽  
Cytochalasin B ◽  
De Novo ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Enzyme Release ◽  
Secretory Product ◽  
Acid Incorporation

The addition of the Ca2+ ionophore A23187 to rabbit neutrophils stimulated [14C]arachidonic acid incorporation into phosphatidylinositol and lysosomal enzyme secretion. A significant increase in phosphatidylinositol labelling was observed after a 2 min exposure to 0.1 microM-ionophore A23187. Maximum increases in rate of labelling were obtained with 1 microM-ionophore A23187 within 1 min, declining to basal rates after 15 min. Similarly, maximum rate of enzyme release occurred during the first 2 min of exposure to ionophore and release was essentially complete by 15 min. Threshold and peak ionophore A23187 concentrations for stimulating both processes were identical. In contrast with the specificity of phosphatidylinositol labelling induced by 1 microM-ionophore A23187 in the absence of cytochalasin B, ionophore also significantly stimulated labelling of phosphatidylserine and phosphatidylethanolamine in the presence of cytochalasin B. With a threshold ionophore concentration (0.1 microM), the enhanced incorporation of arachidonate was relatively specific for phosphatidylinositol in cytochalasin-treated cells. Ionophore A23187 did not accelerate labelling of phosphatidylinositol by [14C]acetate or [14C]glycerol, indicating that ionophore A23187 does not stimulate phosphatidylinositol synthesis de novo, although it did promote [14C]palmitate and [32P]Pi incorporation into neutrophil phosphatidylinositol. However, the increase in phosphatidylinositol labelling with these latter precursors was generally slower in onset and much more modest in magnitude than that observed with arachidonic acid. These results support the hypothesis that a Ca2+-dependent phospholipase, which acts on the arachidonate moiety of phosphatidylinositol, is responsible for initiating at least certain of the membrane events coupled to the release of secretory product from the neutrophil.

FMLP-induced enzyme release from neutrophils: a role for intracellular calcium

1983 ◽  
Vol 245 (3) ◽  
pp. C196-C202 ◽  
Author(s):  
D. Chandler ◽  
G. Meusel ◽  
E. Schumaker ◽  
C. Stapleton
Keyword(s):  
Intracellular Calcium ◽  
Cytochalasin B ◽  
Calcium Ionophore ◽  
Cell Ultrastructure ◽  
Calcium Ionophore A23187 ◽  
Extracellular Calcium ◽  
Ionophore A23187 ◽  
Enzyme Release ◽  
Calcium Depletion ◽  
Dose Dependent

The ability of the chemotactic peptide N-formylmethionyl-leucyl-phenylalanine (FMLP) to stimulate beta-glucuronidase release and 45Ca2+ release from rabbit neutrophils was studied. FMLP stimulated enzyme release from cytochalasin B-treated cells either in the presence or the absence of extracellular calcium. Depletion of cell calcium, by exposure to either ethyleneglycol-bis(beta-aminoethylether)-N,N'-tetraacetic acid or the calcium ionophore A23187, blocked the ability of FMLP to stimulate enzyme release and 45Ca2+ release in the absence of extracellular calcium. The ability of A23187 to lower the 45Ca2+ content of neutrophils, to block FMLP-stimulated 45Ca2+ release, and to inhibit FMLP-stimulated enzyme release in the absence of calcium was dose dependent over the same concentration range (10(-8) to 10(-6) M A23187) for all three actions. In contrast, FMLP stimulated enzyme release from A23187-treated cells, provided that extracellular calcium was present. This secretory response was normal as judged by cell ultrastructure and FMLP dose-response relationships. It is concluded that A23187 depletes a pool of intracellular calcium usually released by FMLP and that release of calcium from this pool is necessary for initiation of enzyme secretion in the absence of extracellular calcium.

scholarly journals Microfilaments and microtubules in calcium ionophore-induced secretion of lysosomal enzymes from human polymorphonuclear leukocytes.

1978 ◽  
Vol 78 (3) ◽  
pp. 769-781 ◽  
Author(s):  
S Hoffstein ◽  
G Weissmann
Keyword(s):  
Plasma Membrane ◽  
Lysosomal Enzymes ◽  
Cytochalasin B ◽  
Human Peripheral Blood ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Microtubule Assembly ◽  
Ionophore A23187 ◽  
Enzyme Release ◽  
Experimental Conditions

Human peripheral blood leukocytes (PMN) are induced to release lysosomal enzymes by the calcium ionophore A23187 in the presence but not the absence of extracellular Ca++. Whereas secretion induced by particulate or immune stimuli is accompanied by an increase in visible microtubules and is inhibitable by colchicine, secretion induced by A23187 and Ca++ was not accompanied by an increase in microtubule numbers and was not inhibited by colchicine. Ca++ did not appear to regulate microtubule assembly in these cells since resting PMN had a mean of 22.3 +/- 2.0 microtubules in the centriolar region as compared to 22.3 +/- 1.1 in ionophore-treated cells and 24.9 +/- 1.5 in cells exposed to ionophore and 1 mM Ca++. Bipolar filaments, 10 nm thick and 300--400 nm long, were numerous in the pericortical cytoplasm of cells exposed to both reagents. Microtubules in these cells were decorated with an electron-opaque fibrillar material. PMN exposed to A23187 and Ca++ were contracted in two directions at right angles to each other: (a) Contractions parallel to the plasma membrane resulted in extensive plication of the cell membrane. The cytoplasm subjacent to the plicae contained dense filamentous webs. Plication was prevented by cytochalasin B or reversed by subsequent exposure to an endocytic stimulus such as zymosan. (b) Contractions perpendicular to the plasma membrane, toward the cytocenter, resulted in the formation of vacuoles in normal PMN and of membrane invaginations in cytochalasin B-treated PMN. Whereas contractions parallel to the plasma membrane could occur in the absence of enzyme release (ionophore alone) and enzyme release could occur in the absence of such contractions (ionophore plus calcium plus cytochalasin B), contraction toward the cytocenter occurred in all experimental conditions in which significant enzyme release was obtained. Thus, lysosomal enzyme secretion in PMN involves contractile movements in the plasma membrane toward the lysosomes rather than the reverse. These calcium-mediated contractile events are mediated by cytochalasin B-insensitive microfilaments but not by microtubule assembly.

Localization of a pigment-containing structure near the surface of Xenopus eggs which contracts in response to calcium

Development ◽  
1983 ◽  
Vol 76 (1) ◽  
pp. 51-65
Author(s):  
R. W. Merriam ◽  
R. A. Sauterer
Keyword(s):  
Calcium Ion ◽  
Cytochalasin B ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Isolation Medium ◽  
Whole Cells ◽  
Transmission Electron ◽  
Structural Connections ◽  
Contractile Structure

Contractions in surface structures of Xenopus eggs have been induced by application of the calcium ionophore A23187 or calcium ion. Local applications have shown that the contractile structure is present in both animal and vegetal hemispheres. It is, however, much stronger in the animal hemisphere and pigment embedded in it there defines the animal half. The injection of cytochalasin B (CB) into whole cells or the application of the antibiotic to half cells cannot prevent the induced contractions. By experimental means, the contraction of a deeper, pigment-containing structure can be uncoupled from a thin, more superficial and relatively pigment-free layer on the egg surface. By this means it has been possible to establish that the CB-resistant contraction is due, at least partially, to a structurally distinguishable layer subjacent to the outer egg cortex. Scanning and transmission electron microscopy demonstrate a dense grainy matrix near the egg surface in which pigment granules but little yolk are embedded. This structure is much thicker in the pigmented hemisphere. The presence of calcium ions in an isolation medium are shown to cause a loosening or dissolution of the structural connections between the dense, contractile structure near the surface and the cytoskeleton of the endoplasm.

Reduced prostacyclin formation after reoxygenation of anoxic endothelium

1990 ◽  
Vol 259 (5) ◽  
pp. C738-C745 ◽  
Author(s):  
S. L. Hempel ◽  
D. L. Haycraft ◽  
J. C. Hoak ◽  
A. A. Spector
Keyword(s):  
Arachidonic Acid ◽  
Umbilical Vein ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
High Rate ◽  
Ionophore A23187 ◽  
Arachidonic Acid Release ◽  
Cyclooxygenase Activity ◽  
Platelet Adherence ◽  
Acid Release

Human umbilical vein endothelial cells subjected to 24 h of anoxia followed by reoxygenation released less prostacyclin (PGI2) in response to thrombin, calcium ionophore A23187, or arachidonic acid. This was associated with a substantial increase in stimulated platelet adherence. Increased lactate dehydrogenase and 51Cr release occurred after 1 h of reoxygenation, but the high rate of release did not persist during the subsequent 23 h of reoxygenation. The changes in platelet adherence and PGI2 release partially resolved over 24 h. PGI2 formation from prostaglandin H2 was not reduced, suggesting that cyclooxygenase activity, but not prostacyclin synthase, is affected by reoxygenation. A decrease in arachidonic acid release from cellular lipids also occurred. The reduction in cyclooxygenase activity, but not arachidonic acid release, was prevented by the presence of ibuprofen during reoxygenation. Addition of catalase or superoxide dismutase during reoxygenation increased PGI2 release but did not completely overcome the reduction relative to control cultures. These findings suggest that the increase in platelet adherence during reoxygenation may be mediated in part by a change in cyclooxygenase activity. This is only partly overcome by extracellular oxygen species scavengers but is prevented by the presence of a reversible cyclooxygenase inhibitor during reoxygenation.

scholarly journals Endothelial Cell “Memory” of Inflammatory Stimulation: Human Venular Endothelial Cells Store Interleukin 8 in Weibel-Palade Bodies

1998 ◽  
Vol 188 (9) ◽  
pp. 1757-1762 ◽  
Author(s):  
Barbara Wolff ◽  
Alan R. Burns ◽  
James Middleton ◽  
Antal Rot
Keyword(s):  
Endothelial Cells ◽  
Secretory Pathway ◽  
De Novo ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Inflammatory Stimuli ◽  
Regulated Secretory Pathway ◽  
Von Willebrand ◽  
Willebrand Factor

The expression and secretion of interleukin (IL)-8, the prototype member of the C-X-C subfamily of chemokines, can be induced by diverse inflammatory stimuli in many cells, including endothelial cells (EC). Upon de novo synthesis, IL-8 localizes intracellularly in the Golgi apparatus, from where it is secreted. In addition to this constitutive secretory pathway, we describe a depot storage and separate regulated secretory pathway of IL-8 in EC. The prolonged stimulation of primary human EC with inflammatory mediators resulted in the accumulation of IL-8 in Weibel-Palade bodies, where it colocalized with von Willebrand factor. IL-8 was retained in these storage organelles for several days after the removal of the stimulus and could be released by EC secretagogues such as phorbol myristate acetate, the calcium ionophore A23187, and histamine. These findings suggest that storage of IL-8 in Weibel-Palade bodies may serve as the EC “memory” of a preceding inflammatory insult, which then enables the cells to secrete IL-8 immediately without de novo protein synthesis.

scholarly journals Calcium ionophore A23187 as a regulator of gene expression in mammalian cells.

1986 ◽  
Vol 103 (6) ◽  
pp. 2145-2152 ◽  
Author(s):  
E Resendez ◽  
J Ting ◽  
K S Kim ◽  
S K Wooden ◽  
A S Lee
Keyword(s):  
Mammalian Cells ◽  
De Novo ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Similar Response ◽  
Calmodulin Antagonist ◽  
Induction Process ◽  
Continuous Presence ◽  
Lower Magnitude

The calcium ionophore A23187 can reversibly induce the expression of two glucose-regulated genes, p3C5 and p4A3. This induction requires a continuous presence of the ionophore for over 2 h. Although extracellular Ca2+ is important for the optimal effect of A23187, it is not necessary for the induction, since a similar response with a lower magnitude can be triggered in cells cultured in low Ca2+ medium buffered with EGTA. Both the basal and induced levels of p3C5 and p4A3 transcripts can be modulated by the calmodulin antagonist W-7, indicating the involvement of Ca2+/calmodulin-associated pathways. In addition, the sensitivity of the A23187 induction to cycloheximide suggests that the induction process is dependent on de novo protein synthesis.

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