scholarly journals Early plasma-membrane-potential changes during stimulation of lymphocytes by concanavalin A.

1983 ◽  
Vol 210 (3) ◽  
pp. 885-891 ◽  
Author(s):  
S M Felber ◽  
M D Brand
Keyword(s):  
Plasma Membrane ◽  
Membrane Potential ◽  
Concanavalin A ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
K Channel ◽  
Ionophore A23187 ◽  
Resting Cells ◽  
Plasma Membrane Potential ◽  
Stimulation Of

1. We have monitored the plasma-membrane potential of lymphocytes by measuring the accumulation of the lipophilic cation methyltriphenylphosphonium (TPMP+) in the presence of the uncoupler carbonyl cyanide p-trifluoromethoxyphenylhydrazone (FCCP). 2. The mitogen concanavalin A causes a decrease in TPMP+ accumulation by pig lymphocytes corresponding to a 3 mV depolarization with 2 1/2 min. Concanavalin A does not alter 86Rb+ uptake in the first 30 min. 3. In contrast concanavalin A increased TPMP+ accumulation and the rate of Rb+ uptake in mouse thymocytes. This is consistent with a previous proposal that the mitogen induces a hyperpolarization of mouse thymocytes as a result of stimulation of a Ca2+-dependent K+ channel. 4. Studies with the calcium ionophore A23187 and quinine (an inhibitor of the Ca2+-dependent K+ channel) suggest that the channel is partially closed in mouse resting thymocytes but is almost fully active in pig resting cells. Thus concanavalin A hyperpolarizes mouse thymocytes by activating the Ca2+-dependent K+ channel but cannot do so in pig lymphocytes because the channel is already maximally activated. 5. The 3mV depolarization of pig cells cannot be explained by a decrease in electrogenic K+ permeability.

scholarly journals Concanavalin A causes an increase in sodium permeability and intracellular sodium content of pig lymphocytes

1983 ◽  
Vol 210 (3) ◽  
pp. 893-897 ◽  
Author(s):  
S M Felber ◽  
M D Brand
Keyword(s):  
Plasma Membrane ◽  
Membrane Potential ◽  
Concanavalin A ◽  
Permeability Coefficient ◽  
Sodium Content ◽  
Intracellular Sodium ◽  
Resting Cells ◽  
Sodium Permeability ◽  
Induced Changes ◽  
Stimulation Of

1. The 3mV depolarization of pig lymphocytes observed within 2 1/2 min of treatment with concanavalin A [Felber & Brand (1983) Biochem. J. 210, 885-891] is dependent on the presence of high extracellular [Na+]. 2. The concanavalin A-induced changes in membrane potential at high and low extracellular [Na+] are quantitatively explained by an increase in the electrogenic permeability coefficient for Na+ (PNa). This rises from a negligible value in resting cells to around 4% of the permeability coefficient for K+ or Cl- in stimulated cells. 3. Concanavalin A induces a 4mM increase in the Na+ content of pig lymphocytes. This increase in intracellular [Na+] is not due solely to stimulation of electrogenic Na+ influx resulting from the rise in PNa. 4. Thus concanavalin A stimulates both an electrogenic pathway for Na+ influx, resulting in a small depolarization of the plasma membrane, and a non-electrogenic Na+ influx pathway, resulting in a rise in intracellular [Na+].

Patterns of calcium localization in pancreatic endocrine cells

1976 ◽  
Vol 21 (1) ◽  
pp. 107-117
Author(s):  
M. Ravazzola ◽  
F. Malaisse-Lagae ◽  
M. Amherdt ◽  
A. Perrelet ◽  
W.J. Malaisse ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
B Cells ◽  
Endocrine Cells ◽  
Secretory Granules ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Calcium Localization ◽  
A Cells ◽  
D Cells

Subcellular calcium localization in the dndocrine cells of rat pancreas was studied by the pyroantimonate precipitation technique. Calcium-containing electron-dense deposits in the endocrine cells were mostly found within secretory granules and along the plasma membrane, but their pattern of distribution in A-, B- and D-cells displayed qualitative and quantitative differences. In B-cells, numerous secretory granules contained deposits located in the halo surrounding the granule core. In A-cells, only few granules contained precipitates in their halo, whereas in D-cells, deposits were situated in the dense core of the secretory granules. Deposits along the plasma membrane occurred generally on the outer leaflet of the plasma membrane of B- and D-cells and on the inner leaflet of that of A-cells. In islets incubated at a high glucose concentration or in the presence of the calcium ionophore A23187, the number of beta granules containing precipitates was significantly increased. By contrast, only few deposits were observed in B-cells incubated in calcium-deprived medium enriched with EGTA. These findings indicate that: the pattern of calcium localization varies in different islet cell types; in B-cells the secretory granules represent one of the major stores of intracellular calcium; and that this store undergoes changes in conditions which alter insulin release.

Differential control of type-I iodothyronine deiodinase expression by the activation of the cyclic AMP and phosphoinositol signalling pathways in cultured human thyrocytes

1995 ◽  
Vol 14 (2) ◽  
pp. 171-177 ◽  
Author(s):  
S G Beech ◽  
S W Walker ◽  
J R Arthur ◽  
D Lee ◽  
G J Beckett
Keyword(s):  
Cyclic Amp ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Signalling Pathways ◽  
Cell Labelling ◽  
Ionophore A23187 ◽  
Type I ◽  
Iodothyronine Deiodinase ◽  
Differential Control ◽  
Stimulation Of

ABSTRACT The effects of TSH and the activation of the cyclic AMP (cAMP) and Ca2+-phosphatidylinositol (Ca2+-PI) cascades on the activity and expression of the selenoenzyme thyroidal type-I iodothyronine deiodinase (ID-I) have been studied using human thyrocytes grown in primary culture. Stimulation of ID-I activity and expression was obtained with TSH and an analogue of cAMP, 8-bromo-cAMP. In the presence or absence of TSH, the addition of the phorbol ester, phorbol 12-myristate 13-acetate (PMA) together with the calcium ionophore A23187, caused a decrease in ID-I activity; a decrease in ID-I expression was also observed as assessed by cell labelling with [75 Se]selenite. PMA alone had no effect on ID-I activity in the presence or absence of TSH. A23187 alone produced a small but significant reduction in ID-I activity, but only in TSH-stimulated cells. These data provide evidence that the expression of thyroidal ID-I is negatively regulated by the Ca2+-PI cascade, and positively regulated by the cAMP cascade.

scholarly journals Interrelationships of polymorphonuclear neutrophil membrane-bound calcium, membrane potential, and chemiluminescence: studies in single living cells

Blood ◽  
1984 ◽  
Vol 64 (6) ◽  
pp. 1184-1192 ◽  
Author(s):  
GW Sullivan ◽  
GR Donowitz ◽  
JA Sullivan ◽  
GL Mandell
Keyword(s):  
Membrane Potential ◽  
Calcium Release ◽  
Calcium Ionophore ◽  
Image Intensifier ◽  
Calcium Ionophore A23187 ◽  
Polymorphonuclear Neutrophil ◽  
Human Neutrophils ◽  
Ionophore A23187 ◽  
Ionic Fluxes ◽  
Single Living

Abstract Stimulated neutrophils show ionic fluxes that may function as “transducers” between stimuli and effector functions. Using fluorescent probes, patterns of membrane-associated calcium (chlortetracycline, CTC) and membrane potential (3–3′-dipentyloxacarbocyanine, di-O-C5 (3)) in single living human neutrophils were observed with a fluorescence microscope fitted with an image intensifier and photometer. Fluorescence changes were related to chemiluminescence. In unstimulated neutrophils, CTC and di-O-C5 (3) fluorescence was brightest in the perinuclear region. Di-O-C5 (3) fluorescence was also seen in mitochondria. Neutrophil stimulation with zymosan, phorbol myristate acetate (PMA) or calcium ionophore (A23187) resulted in loss of di-O-C5 (3) and CTC fluorescence and chemiluminescence proportional to the strength of the stimulus. Experiments demonstrated the independence of these processes. (1) Digitonin stimulation caused chemiluminescence and di-O-C5 (3) darkening without loss of CTC fluorescence. (2) Depolarization of neutrophils did not induce CTC darkening or chemiluminescence. (3) Calcium ionophore (A23187) stimulation of neutrophils in calcium-free medium resulted in normal di-O-C5 (3) and CTC darkening, but a blunted chemiluminescence peak. (4) Calcium ionophore (A23187) stimulated the loss of di-O-C5 (3) and CTC fluorescence from chronic granulomatous disease neutrophils, but did not trigger an oxidative burst. Although neutrophil depolarization, calcium release from membranes, and oxidative activity are linked, these processes can clearly be separated.

scholarly journals Stimulation of CEACAM1 expression by 12- O -tetradecanoylphorbol-13-acetate (TPA) and calcium ionophore A23187 in endometrial carcinoma cells

2005 ◽  
Vol 27 (3) ◽  
pp. 483-490 ◽  
Author(s):  
Ana-Maria Bamberger ◽  
Juliane Briese ◽  
Julica Götze ◽  
Insa Erdmann ◽  
Heinrich M. Schulte ◽  
...  
Keyword(s):  
Endometrial Carcinoma ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Carcinoma Cells ◽  
Ionophore A23187 ◽  
Stimulation Of

Effects of hypothermic liquid storage and cryopreservation on basal and induced plasma membrane phospholipid disorder and acrosome exocytosis in boar spermatozoa

2005 ◽  
Vol 17 (4) ◽  
pp. 467 ◽  
Author(s):  
H. D. Guthrie ◽  
G. R. Welch
Keyword(s):  
Plasma Membrane ◽  
Acrosome Reaction ◽  
Calcium Ionophore ◽  
Fluorescein Isothiocyanate ◽  
Calcium Ionophore A23187 ◽  
Membrane Phospholipid ◽  
Ionophore A23187 ◽  
Liquid Storage ◽  
Boar Spermatozoa ◽  
Plasma Membrane Phospholipid

Flow cytometry was utilised to determine whether short-term (Day 1) or long-term hypothermic liquid storage (Day 5), or cryopreservation of boar spermatozoa (1) caused changes in plasma membrane phospholipid disorder (MPLD) and acrosome exocytosis (AE), indicative of an advanced stage of capacitation or acrosome status, and (2) facilitated or inhibited the induction of capacitation and the acrosome reaction. Merocyanine with Yo-Pro-1 and peanut agglutinin–fluorescein isothiocyanate with propidium iodide were used to identify MPLD and AE, respectively, in viable spermatozoa. The incidence of basal sperm MPLD and AE in fresh semen was very low (1.1 and 2.2%, respectively) and was increased (P < 0.05) only a small amount in Day 5 and cryopreserved semen (3–8%). Compared to no bicarbonate, incubation with bicarbonate increased MPLD, but the response was greatest (P < 0.05) in fresh sperm (52.3%) compared with Day 1 (36.6%), Day 5 (13.9%) and cryopreserved sperm (13.6%). Incubation with calcium ionophore A23187 increased AE in spermatozoa, but the response was less (P < 0.05) for fresh (34%) and cryopreserved (27%) semen than for Day 1 (45%) and Day 5 (57%) semen. In summary, hypothermic liquid storage and cryopreservation of boar spermatozoa did not advance capacitation or acrosome status in viable spermatozoa, but did alter their responses to induction of capacitation and the acrosome reaction.

scholarly journals Interactions between human eosinophils and schistosomula of schistosoma mansoni. II. The mechanism of irreversible eosinophil adherence

1979 ◽  
Vol 150 (6) ◽  
pp. 1456-1471 ◽  
Author(s):  
AE Butterworth ◽  
MA Vadas ◽  
DL Wassom ◽  
A Dessein ◽  
M Hogan ◽  
...  
Keyword(s):  
Schistosoma Mansoni ◽  
Concanavalin A ◽  
Protein A ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Con A ◽  
Normal Human ◽  
Culture Supernate ◽  
Eosinophil Major Basic Protein

Previous work (1)(1) has shown that normal human eosinophils show a preferential capacity, in comparison with neutrophils, to bind to antibody- coated schistosomula of Schistosoma mansoni. This effect is attributable to a temperature-dependent function of the eosinophil which renders its binding stable and irreversible by aggregated gamma globulin or Staphylococcus aureus protein A. In contrast, the binding of neutrophils is readily reversible by these agents. It has now been shown that the differences observed between eosinophils and neutrophils is a property of their interaction with living schistosomula. When dead or artificially damaged schistosomula were tested, neutrophils showed a markedly enhanced capacity to adhere, in both the presence and absence of anti-chistosomular serum. Subsequent experiments were designed to test the hypothesis that the strong, stable binding of eosinophils was attributable to degranulation, with release of granule contents which would then serve as ligands to bind the cell to the organism. First, an enhanced adherence both of eosinophils and of neutrophils could be demonstrated in the presence of eosinophil major basic protein (MBP) or of protamine, a high molecular weight cation. Second, the binding of eosinophils induced by concanavalin A (Con A) was found to differ markedly from that induced by antischistosomular serum. Con A-mediated binding of eosinophils was fully reversible by alpha-methyl-mannoside, was not associated with damage to the organism, and did not lead to degranulation of the cell, as estimated by measuring the release of MBP into the culture supernate. However, induction of degranulation of concanavalin A-bound eosinophils, but not of neutrophils, with the calcium ionophore A23187 converted the reaction into one which was no longer reversible by alpha- methylmannoside and in which damage to the organism now did occur. These findings support the hypothesis that the stable binding of eosinophils is associated with degranulation, a process which may contribute to the preferential capacity of this cell to mediate antibody-dependent damage to schistosomula.

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