scholarly journals Dissociation of intracellular lysosomal rupture from the cell death caused by silica

1980 ◽  
Vol 87 (3) ◽  
pp. 643-651 ◽  
Author(s):  
AB Kane ◽  
RP Stanton ◽  
EG Raymond ◽  
ME Dobson ◽  
ME Knafelc ◽  
...  
Keyword(s):  
Cell Death ◽  
Horseradish Peroxidase ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Permeability Barrier ◽  
Ionophore A23187 ◽  
Plasma Membrane Permeability ◽  
Orange Fluorescence ◽  
Total Dna ◽  
The Relationship

The relationship between intracellular lysosomal rupture and cell death caused by silica was studied in P388d(1) macrophages. After 3 h of exposure to 150 μg silica in medium containing 1.8 mM Ca(2+), 60 percent of the cells were unable to exclude trypan blue. In the absence of extracellular Ca(2+), however, all of the cells remained viable. Phagocytosis of silica particles occurred to the same extent in the presence or absence of Ca(2+). The percentage of P388D(1) cells killed by silica depended on the dose and the concentration of Ca(2+) in the medium. Intracellular lyosomal rupture after exposure to silica was measured by acridine orange fluorescence or histochemical assay of horseradish peroxidase. With either assay, 60 percent of the cells exposed to 150 μg silica for 3 h in the presence of Ca(2+) showed intracellular lysosomal rupture, was not associated with measureable degradation of total DNA, RNA, protein, or phospholipids or accelerated turnover of exogenous horseradish peroxidase. Pretreatment with promethazine (20 μg/ml) protected 80 percent of P388D(1) macrophages against silica toxicity although lysosomal rupture occurred in 60-70 percent of the cells. Intracellular lysosomal rupture was prevented in 80 percent of the cells by pretreatment with indomethacin (5 x 10(-5)M), yet 40-50 percent of the cells died after 3 h of exposure to 150 μg silica in 1.8 mM extracellular Ca(2+). The calcium ionophore A23187 also caused intracellular lysosomal rupture in 90-98 percent of the cells treated for 1 h in either the presence or absence of extracellular Ca(2+). With the addition of 1.8 mM Ca(2+), 80 percent of the cells was killed after 3 h, whereas all of the cells remained viable in the absence of Ca(2+). These experiments suggest that intracellular lysosomal rupture is not causally related to the cell death cause by silica or A23187. Cell death is dependent on extracellular Ca(2+) and may be mediated by an influx of these ions across the plasma membrane permeability barrier damaged directly by exposure to these toxins.

In vitro induction of the acrosome reaction in ovine spermatozoa by calcium ionophore A23187

2003 ◽  
Vol 51 (1) ◽  
pp. 103-109 ◽  
Author(s):  
Ö. Uçar ◽  
T. J. Parkinson
Keyword(s):  
Phase Contrast ◽  
Acrosome Reaction ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Contrast Microscopy ◽  
The Relationship ◽  
In Vitro Induction ◽  
Artificial Vagina

The relationship between concentration of calcium ionophore A23187 and incubation time upon the proportion of spermatozoa undergoing acrosome reaction (AR) in vitro was investigated in rams from a commercial artificial insemination (AI) program. Two ejaculates were collected by artificial vagina from each of nine rams of three breeds (Finn Dorset, Charolais and Suffolk) aged 8-36months. Each ejaculate was diluted in a skimmed milk extender. Spermatozoa were thereafter incubated for 45 or 60min in modified Tyrode's medium (TALP) which contained either zero, 0.1 or 1.0µM/l A23187. After fixing in 10% formaldehyde, the number of spermatozoa that had undergone AR was determined by phase contrast microscopy. In pre-incubation samples, 21.3± 3.3% of spermatozoa had undergone AR. Percentages of acrosome reacted spermatozoa were significantly (P<0.001) increased after incubation with A23187. After incubation with 0.1µM/l A23187 for 45 and 60min there were 22.4±3.0% and 31.7±4.3% acrosome reacted spermatozoa, respectively. After incubation with 1.0µM/l A23187 for 45 and 60min there were 46.2±6.5% and 53.8±5.9% acrosome reacted spermatozoa, whilst corresponding numbers in control samples were 17.0±2.7% and 22.3±4.2%. There was also a significant (P<0.001) effect of individual animals upon the responses to different concentrations of A23187. These findings indicate that (i) A23187 can be used to assess the AR of ovine spermatozoa in vitro and (ii) there are effects of individual animals upon the proportion of spermatozoa undergoing AR.

The relationship between secretion and intracellular free calcium in bovine adrenal chromaffin cells

1984 ◽  
Vol 4 (7) ◽  
pp. 605-611 ◽  
Author(s):  
Robert D. Burgoyne
Keyword(s):  
Chromaffin Cells ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Catecholamine Release ◽  
Intracellular Free Calcium ◽  
Free Calcium ◽  
Ionophore A23187 ◽  
Adrenal Chromaffin Cells ◽  
Adrenal Chromaffin ◽  
The Relationship

The effect of carbamylcholine and the calcium ionophore A23187 on catecholamine release and intracellular free calcium, [Ca2+]i, in bovine adrenal chromaffin cells was determined. At 10−4M carbamylcholine maximal release occurred with an accompanying increase in [Ca2+]i from a basal level of 168 nM to less than 300 nM. An increase in [Ca2+]i of a similar magnitude was found following challenge with 40 nM A23187. However, in this case, no catecholamine release occurred. These results suggest that stimulation of secretion from chromaffin cells by carbamylcholine may involve additional triggers which stimulate secretion at low [Ca2+]i.

scholarly journals The calcium ionophore A23187 increases the tight-junctional permeability in rat liver

1988 ◽  
Vol 256 (3) ◽  
pp. 1039-1041 ◽  
Author(s):  
K S Kan ◽  
R Coleman
Keyword(s):  
Horseradish Peroxidase ◽  
Rat Liver ◽  
Bile Flow ◽  
Calcium Ionophore ◽  
Peak Height ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Hepatocellular Damage ◽  
Junctional Permeability ◽  
Second Peak

The effect of an increase in intracellular Ca2+ concentration on tight-junctional permeability in rat liver was studied by using the calcium ionophore A23187. Infusion of 100 microliters of dimethyl sulphoxide containing various amounts of A23187 over 30 min into isolated perfused livers was followed by a pulse of horseradish peroxidase (HRP) under single-pass conditions. The first biliary HRP peak, a measure of junctional permeability, was increased 4-fold with 100 micrograms of A23187. There were, however, no significant effects on bile flow or on aspartate aminotransferase leakage as compared with the control at this dosage, and thus the increase in junctional permeability was occurring without evidence of appreciable cholestatic or hepatocellular damage. Higher dosages of A23187, however, caused not only an increase in HRP peak height but also changes in bile flow and increases in aminotransferase leakage, indicating more extensive effects at these higher dosages. A second peak of HRP secretion, occurring 20-25 min after the HRP pulse, was also elevated approx. 3.5-fold; this may indicate that pinocytosis and transcellular movement of HRP are also increased under these conditions.

Growth factors and the primary cilium in BALB/c 3T3 cells

1987 ◽  
Vol 45 ◽  
pp. 830-831
Author(s):  
R. W. Tucker ◽  
N. S. More ◽  
S. Jayaraman
Keyword(s):  
Growth Factors ◽  
Primary Cilium ◽  
Cultured Cells ◽  
Morphological Changes ◽  
Calcium Ionophore ◽  
Growth Stimulation ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
3T3 Cells ◽  
Microtubule Depolymerization

The mechanisms by which polypeptide growth factors Induce DNA synthesis in cultured cells is not understood, but morphological changes Induced by growth factors have been used as clues to Intracellular messengers responsible for growth stimulation. One such morphological change has been the transient disappearance of the primary cilium, a “9 + 0” cilium formed by the perinuclear centriole in interphase cells. Since calcium ionophore A23187 also produced both mitogenesis and ciliary changes, microtubule depolymerization might explain ciliary disappearance monitored by indirect immunofluorescence with anti-tubulin antibody. However, complete resorption and subsequent reformation of the primary cilium occurs at mitosis, and might also account for ciliary disappearance induced by growth factors. To settle this issue, we investigated the ultrastructure of the primary cilium using serial thin-section electron microscopy of quiescent BALB/c 3T3 cells before and after stimulation with serum.

Inhibition of Platelet Aggregation by Ethanol in Vitro Shows Specificity for Aggregating Agent Used and Is Influenced by Platelet Lipid Composition

1982 ◽  
Vol 48 (01) ◽  
pp. 049-053 ◽  
Author(s):  
C G Fenn ◽  
J M Littleton
Keyword(s):  
Platelet Aggregation ◽  
Lipid Composition ◽  
Saturated Fatty Acids ◽  
Calcium Ionophore ◽  
Cholesterol Content ◽  
Membrane Lipid ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Increased Sensitivity

SummaryEthanol at physiologically tolerable concentrations inhibited platelet aggregation in vitro in a relatively specific way, which may be influenced by platelet membrane lipid composition. Aggregation to collagen, calcium ionophore A23187 and thrombin (low doses) were often markedly inhibited by ethanol, adrenaline and ADP responses were little affected, and aggregation to exogenous arachidonic acid was actually potentiated by ethanol. Aggregation to collagen, thrombin and A23187 was inhibited more by ethanol in platelets enriched with saturated fatty acids than in those enriched with unsaturated fats. Platelets enriched with cholesterol showed increased sensitivity to ADP, arachidonate and adrenaline but this increase in cholesterol content did not appear to influence the inhibition by ethanol of platelet responses. The results suggest that ethanol may inhibit aggregation by an effect on membrane fluidity and/or calcium mobilization resulting in decreased activity of a membrane-bound phospholipase.

Effects of glucocorticoids on prostaglandin formation by human amnion

1990 ◽  
Vol 68 (6) ◽  
pp. 671-676 ◽  
Author(s):  
William Gibb ◽  
Jean-Claude Lavoie
Keyword(s):  
Calcium Ionophore ◽  
Inhibitory Effect ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Isolated Cells ◽  
Stimulatory Action ◽  
Human Amnion ◽  
Human Labor ◽  
Epidermal Growth

The human amnion may be an important source of prostaglandins involved in the onset of human labor and therefore it is important to define the factors that regulate their formation in this tissue. In the present study we demonstrate that glucocorticoids inhibit prostaglandin production by freshly isolated amnion cells. The inhibitory action of the glucocorticoids, however, changes to a stimulatory action when the cells are maintained in primary culture for a few days. For both inhibition and stimulation, concentrations of 10−8 M dexamethasone or greater were required to give significant effects, and estradiol and progesterone had no effect on the prostaglandin output of the cells. Epidermal growth factor (EGF), which has previously been found to stimulate prostaglandin output by confluent amnion cells, did not alter prostaglandin output of cells initially placed in culture. Furthermore, the stimulatory action of EGF and dexamethasone appeared additive. The calcium ionophore A23187 stimulated prostaglandin output in freshly isolated cells and accentuated the inhibitory effect of dexamethasone. These studies indicate that prostaglandin formation by human amnion during pregnancy could be regulated by glucocorticoids. These steroids are easily available to the amnion by way of cortisone conversion to Cortisol by the maternal decidua. The results also indicate that amnion is capable of responding to glucocorticoids in both a stimulatory and inhibitory fashion and whether one or both actions are of importance in vivo is a question that is as yet unresolved.Key words: prostaglandins, amnion, fetal membranes, glucocorticoids, labor, pregnancy.

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