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 Is a rise in intracellular concentration of free calcium necessary or sufficient for stimulated cytoskeletal-associated actin?

1986 ◽  
Vol 102 (4) ◽  
pp. 1459-1463 ◽  
Author(s):  
R I Sha'afi ◽  
J Shefcyk ◽  
R Yassin ◽  
T F Molski ◽  
M Volpi ◽  
...  
Keyword(s):  
Intracellular Calcium ◽  
Pertussis Toxin ◽  
Incubation Medium ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Extracellular Calcium ◽  
Intracellular Concentration ◽  
The Other ◽  
Free Calcium ◽  
Ionophore A23187

The addition of the calcium ionophore A23187 to rabbit neutrophils increases the amount of actin associated with the cytoskeleton regardless of the presence or absence of calcium in the incubation medium. In the presence of extracellular calcium, the effect of A23187 is biphasic with respect to concentration. The action of the ionophore is rapid, transient, and is inhibited by pertussis toxin, hyperosmolarity, and quinacrine. On the other hand, the addition of pertussis toxin or hyperosmolarity has small if any, effect on the rise in intracellular calcium produced by A23187. While quinacrine does not affect the fMet-Leu-Phe-induced increase in cytoskeletal actin and the polyphosphoinositide turnover, its addition inhibits completely the stimulated increase in Ca-influx produced by the same stimulus. The results presented here suggest that a rise in the intracellular concentration of free calcium is neither necessary nor sufficient for the stimulated increase in cytoskeletal-associated actin. A possible relationship between the lipid remodeling stimulated by chemoattractants and the increased cytoskeletal actin is discussed.

scholarly journals Endogenous and exogenous adenosine inhibit granulocyte aggregation without altering the associated rise in intracellular calcium concentration

Blood ◽  
1988 ◽  
Vol 72 (1) ◽  
pp. 29-33
Author(s):  
KM Skubitz ◽  
NW Wickham ◽  
DE Hammerschmidt
Keyword(s):  
Intracellular Calcium ◽  
Calcium Concentration ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Maximal Inhibition ◽  
Kinase C ◽  
Dose Dependent Fashion ◽  
Granulocyte Function ◽  
Dose Dependent

The effects of adenosine, adenosine deaminase (ADA), and an irreversible ADA inhibitor 2′-deoxycoformycin (DCF) on granulocyte aggregation in response to four different stimuli: the synthetic chemotaxin N-formyl-met-leu-phe (FMLP), zymosan-activated plasma (ZAP), the calcium ionophore A23187, and phorbol myristate acetate (PMA) were studied. Adenosine inhibited granulocyte aggregation in response to 10(- 7) mol/L FMLP in a dose-dependent fashion; inhibition in the presence of 1 mumol/L adenosine was 25% +/- 3% (SD) and was 50% (the maximal inhibition observed) with 1 mmol/L adenosine. Quantitatively similar results were obtained when ZAP or A23187 was used as the aggregant but the response to PMA was not affected. ADA not only reversed the inhibition due to adenosine but actually augmented the aggregation to FMLP by 118% +/- 9%. Similar results were obtained with ZAP and A23187 but not with PMA. These effects of ADA depended on its enzymatic activity as they could be blocked by preincubation with DCF. Fluorescent measurement of intracellular calcium in fura-2 loaded granulocyte suspensions established that neither adenosine nor ADA affected subsequent FMLP-stimulated calcium responses. Adenosine, therefore, may inhibit granulocyte responsiveness by blocking signal transduction at a point after calcium entry/mobilization but before activation of protein kinase C. Furthermore, the augmentation of responses seen with ADA suggests that endogenous adenosine may be a physiologic autocrine regulator of granulocyte function.

scholarly journals Endogenous and exogenous adenosine inhibit granulocyte aggregation without altering the associated rise in intracellular calcium concentration

Blood ◽  
1988 ◽  
Vol 72 (1) ◽  
pp. 29-33 ◽  
Author(s):  
KM Skubitz ◽  
NW Wickham ◽  
DE Hammerschmidt
Keyword(s):  
Intracellular Calcium ◽  
Calcium Concentration ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Maximal Inhibition ◽  
Kinase C ◽  
Dose Dependent Fashion ◽  
Granulocyte Function ◽  
Dose Dependent

Abstract The effects of adenosine, adenosine deaminase (ADA), and an irreversible ADA inhibitor 2′-deoxycoformycin (DCF) on granulocyte aggregation in response to four different stimuli: the synthetic chemotaxin N-formyl-met-leu-phe (FMLP), zymosan-activated plasma (ZAP), the calcium ionophore A23187, and phorbol myristate acetate (PMA) were studied. Adenosine inhibited granulocyte aggregation in response to 10(- 7) mol/L FMLP in a dose-dependent fashion; inhibition in the presence of 1 mumol/L adenosine was 25% +/- 3% (SD) and was 50% (the maximal inhibition observed) with 1 mmol/L adenosine. Quantitatively similar results were obtained when ZAP or A23187 was used as the aggregant but the response to PMA was not affected. ADA not only reversed the inhibition due to adenosine but actually augmented the aggregation to FMLP by 118% +/- 9%. Similar results were obtained with ZAP and A23187 but not with PMA. These effects of ADA depended on its enzymatic activity as they could be blocked by preincubation with DCF. Fluorescent measurement of intracellular calcium in fura-2 loaded granulocyte suspensions established that neither adenosine nor ADA affected subsequent FMLP-stimulated calcium responses. Adenosine, therefore, may inhibit granulocyte responsiveness by blocking signal transduction at a point after calcium entry/mobilization but before activation of protein kinase C. Furthermore, the augmentation of responses seen with ADA suggests that endogenous adenosine may be a physiologic autocrine regulator of granulocyte function.

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.

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.

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.

scholarly journals Rapid ultrastructural changes in the dense tubular system following platelet activation

Blood ◽  
1992 ◽  
Vol 80 (3) ◽  
pp. 718-723 ◽  
Author(s):  
L Ebbeling ◽  
C Robertson ◽  
A McNicol ◽  
JM Gerrard
Keyword(s):  
Intracellular Calcium ◽  
Platelet Activation ◽  
Calcium Ionophore ◽  
Cytosolic Calcium ◽  
Calcium Ionophore A23187 ◽  
Ultrastructural Changes ◽  
Ionophore A23187 ◽  
Tubular System ◽  
Protein Kinase C Activators ◽  
Morphologic Changes

Abstract The dense tubular system (DTS) functions to regulate platelet activation by sequestering or releasing calcium, similar to the sarcotubules of skeletal muscle. In resting platelets, the DTS exists as thin elongated membranes. Within 10 seconds of the addition of thrombin, platelets show a major ultrastructural change in their DTS: from the thin elongated form to a rounded vesicular form. These morphologic changes were demonstrated with two different stains and two different fixation methods. Platelets exposed to the calcium ionophore A23187 showed the same ultrastructural changes in the DTS. In contrast, the DTS remains in a thin elongated form when platelets are stimulated by the protein kinase C activators phorbol 12-myristate 13-acetate (PMA) and oleoylacetylglycerol (OAG). These morphologic changes may be related to the discharge of calcium from the DTS because this is stimulated by thrombin and A23187, but not by PMA. Preincubation of the platelets with the intracellular calcium chelator 5,5′-dimethyl-bis-(0- aminophenoxy)-ethane-N,N,N′,N tetra acetic acid (BAPTA) largely prevented both the thrombin-induced rise in intracellular calcium and the changes in DTS morphology, suggesting that the changes in DTS morphology are secondary to the increase in cytosolic calcium. The results provide a morphologic correlate to existing biochemical evidence showing that the DTS is involved early during paltelet activation.

The effects of HA compound calcium antagonists on delayed cerebral vasospasm in dogs

1986 ◽  
Vol 65 (1) ◽  
pp. 80-85 ◽  
Author(s):  
Masakazu Takayasu ◽  
Yoshio Suzuki ◽  
Masato Shibuya ◽  
Toshio Asano ◽  
Masahiko Kanamori ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Intracellular Calcium ◽  
Cerebral Vasospasm ◽  
Basilar Artery ◽  
Calcium Antagonists ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Delayed Cerebral Vasospasm ◽  
Arterial Blood

✓ The authors have examined the effects of the HA compounds HA1004(N-(2-guanidinoethyl)-5-isoquino-linesulfonamide) and HA1077(l-(5-isoquinolinesulfonyl)homopiperazine), which are intracellular calcium antagonists, on delayed cerebral vasospasm from subarachnoid hemorrhage (SAH). The modes of action of these compounds were compared with those of the more commonly used calcium entry blockers. Calcium ionophore A23187 (4.8 × 10−6 M)-induced contraction of a canine basilar artery strip was completely antagonized by the HA compounds (10−5 M) but not by the entry-blocking calcium antagonists nicardipine, diltiazem, and verapamil (10−5 M), suggesting that the HA compounds act differently. Delayed cerebral vasospasm was induced by a “two-hemorrhage” canine model. The magnitude of the vasospasm and the effects of the HA compounds were determined angiographically. On SAH Day 7, a significant vasospasm was observed in every dog. The diameter of the basilar artery had diminished to 59% ± 2% (mean ± standard error) of the control value obtained before SAH (on Day 1). The intravenous administration of HA1004 caused a mild dilation of the basilar artery of 10% and 11% at doses of 3 and 10 mg/kg, respectively; however, HA1077 produced a more marked dilation of 19% and 27%, respectively, at the same doses. Both of these drugs lowered mean arterial blood pressure to about 80% and 50% at doses of 3 and 10 mg/kg, respectively. Intracisternal administration of the HA compounds (6 mg) completely reversed cerebral vasospasm without much effect on the blood pressure. The intracellular calcium antagonists of the HA compound group appear to be promising agents for the treatment of intractable cerebral vasospasm.

Calcium Ionophore A23187 Stimulates Cytokinin-Like Mitosis in Funaria

Science ◽  
1982 ◽  
Vol 217 (4563) ◽  
pp. 943-945 ◽  
Author(s):  
MARY JANE SAUNDERS ◽  
PETER K. HEPLER
Keyword(s):  
Intracellular Calcium ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Ion Concentration ◽  
Target Cells ◽  
Ionophore A23187 ◽  
Intracellular Calcium Ion ◽  
Calcium Ion Concentration ◽  
Mitotic Regulation ◽  
Bud Initiation

The plant hormone cytokinin stimulates asymmetrical division in target cells of the protonema of the moss Funaria hygrometrica, leading to bud formation. The initial division can be induced in the absence of cytokinin by the calcium ionophore A23187 in medium containing calcium. These findings suggest that increases in the concentration of intracellular calcium are essential to bud initiation. Therefore mitotic regulation by cytokinin may be due, at least in part, to the modulation of intracellular calcium ion concentration.

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