Membrane Changes in Polymorphonuclear Leukocytes During Ionophore (A23187) - Induced Lysosomal Release

1977 ◽  
Vol 35 ◽  
pp. 482-483
Author(s):  
P.L. Moore ◽  
P.L. Sannes ◽  
H.L. Bank ◽  
S.S. Spicer
Keyword(s):  
Structural Changes ◽  
Calcium Release ◽  
Clear Understanding ◽  
Ionophore A23187 ◽  
Enzyme Release ◽  
Extracellular Medium ◽  
Pmn Leukocytes ◽  
Intracellular Ion Concentrations ◽  
Membrane Changes ◽  
Pmn Leukocyte

It is thought that calcium and/or magnesium may play important roles in polymorphonuclear (PMN) leukocyte functions such as chemotaxis, adhesion and phagocytosis. Yet, a clear understanding of the biological roles of these ions has awaited the development of techniques which permit a selective alteration of intracellular ion concentrations. Recently, treatment of cells with the ionophore A23187 has been used to alter intracellular divalent cation concentrations. This ionophore is a lipid soluble antibiotic produced by Streptomyces chartreusensis that complexes with both calcium and magnesium (3) and is believed to carry these ions across biological membranes (4). Biochemical investigations of human PMN leukocytes demonstrate that cells treated with A23187 and extracellular calcium release their lysosomal enzymes into the extracellular medium without rupturing and releasing their soluble cytoplasmic enzymes (5,6). The aim of the present study and and a companion report (7) was to investigate the structural changes that occur in leukocytes during ionophore-induced lysosomal enzyme release.

scholarly journals Cdc42 and Rac Stimulate Exocytosis of Secretory Granules by Activating the Ip3/Calcium Pathway in Rbl-2h3 Mast Cells

2000 ◽  
Vol 148 (3) ◽  
pp. 481-494 ◽  
Author(s):  
Elizabeth Hong-Geller ◽  
Richard A. Cerione
Keyword(s):  
Calcium Release ◽  
Calcium Influx ◽  
Secretory Granules ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Dominant Negative ◽  
Ionophore A23187 ◽  
Ip3 Receptor ◽  
Extracellular Medium

We have expressed dominant-active and dominant-negative forms of the Rho GTPases, Cdc42 and Rac, using vaccinia virus to evaluate the effects of these mutants on the signaling pathway leading to the degranulation of secretory granules in RBL-2H3 cells. Dominant-active Cdc42 and Rac enhance antigen-stimulated secretion by about twofold, whereas the dominant-negative mutants significantly inhibit secretion. Interestingly, treatment with the calcium ionophore, A23187, and the PKC activator, PMA, rescues the inhibited levels of secretion in cells expressing the dominant-negative mutants, implying that Cdc42 and Rac act upstream of the calcium influx pathway. Furthermore, cells expressing the dominant-active mutants exhibit elevated levels of antigen-stimulated IP3 production, an amplified antigen-stimulated calcium response consisting of both calcium release from internal stores and influx from the extracellular medium, and an increase in aggregate formation of the IP3 receptor. In contrast, cells expressing the dominant-negative mutants display the opposite phenotypes. Finally, we are able to detect an in vitro interaction between Cdc42 and PLCγ1, the enzyme immediately upstream of IP3 formation. Taken together, these findings implicate Cdc42 and Rac in regulating the exocytosis of secretory granules by stimulation of IP3 formation and calcium mobilization upon antigen stimulation.

Sarcolemmal permeability changes during early myocardial anoxia

1978 ◽  
Vol 36 (2) ◽  
pp. 642-643
Author(s):  
M. Ashraf ◽  
L. Landa ◽  
L. Nimmo ◽  
C. M. Bloor
Keyword(s):  
Cell Membrane ◽  
Membrane Permeability ◽  
Coronary Artery Occlusion ◽  
Artery Occlusion ◽  
Cell Membrane Permeability ◽  
Enzyme Release ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Sarcolemmal Permeability ◽  
Membrane Changes

Following coronary artery occlusion, the myocardial cells lose intracellular enzymes that appear in the serum 3 hrs later. By this time the cells in the ischemic zone have already undergone irreversible changes, and the cell membrane permeability is variably altered in the ischemic cells. At certain stages or intervals the cell membrane changes, allowing release of cytoplasmic enzymes. To correlate the changes in cell membrane permeability with the enzyme release, we used colloidal lanthanum (La+++) as a histological permeability marker in the isolated perfused hearts. The hearts removed from sprague-Dawley rats were perfused with standard Krebs-Henseleit medium gassed with 95% O2 + 5% CO2. The hypoxic medium contained mannitol instead of dextrose and was bubbled with 95% N2 + 5% CO2. The final osmolarity of the medium was 295 M osmol, pH 7. 4.

scholarly journals Pertussis toxin inhibition of chemotactic factor-induced calcium mobilization and function in human polymorphonuclear leukocytes.

1985 ◽  
Vol 162 (1) ◽  
pp. 145-156 ◽  
Author(s):  
D W Goldman ◽  
F H Chang ◽  
L A Gifford ◽  
E J Goetzl ◽  
H R Bourne
Keyword(s):  
Pertussis Toxin ◽  
Lysosomal Enzyme ◽  
Polymorphonuclear Leukocytes ◽  
Regulatory Protein ◽  
Leukotriene B4 ◽  
Ionophore A23187 ◽  
Enzyme Release ◽  
Adp Ribosylation ◽  
Chemotactic Factors ◽  
Human Polymorphonuclear Leukocytes

Chemotactic factors stimulate a rapid increase in the cytosolic concentration of intracellular calcium ions ([Ca2+]in) in human polymorphonuclear leukocytes (PMNL), which may be an event that is critical to the expression of chemotaxis and other PMNL functions. Treatment of PMNL with pertussis toxin catalyzes ADP-ribosylation of a protein similar or identical to the inhibiting regulatory protein of adenylate cyclase, Gi, and suppresses the increase in [Ca2+]in elicited by leukotriene B4(LTB4) and formyl-methionyl-leucyl-phenylalanine. Chemotactic migration and lysosomal enzyme release elicited by chemotactic factors were inhibited by pertussis toxin with a concentration-dependence similar to that for inhibition of the increase in [Ca2+]in, without an effect on lysosomal enzyme release induced by the ionophore A23187 and phorbol myristate acetate. Activated pertussis toxin catalyzed the [32P]ADP-ribosylation of a 41 kD protein in homogenates of PMNL. The extent of [32P]ADP-ribosylation of this protein was reduced 59% by pretreatment of intact PMNL with pertussis toxin. Pertussis toxin selectively decreased the number of high-affinity receptors for LTB4 on PMNL by 60% without altering the number or binding properties of the low-affinity subset of receptors. Pertussis toxin modification of a membrane protein of PMNL analogous to Gi thus simultaneously alters chemotactic receptors and attenuates the changes in cytosolic calcium concentration and PMNL function caused by chemotactic factors.

scholarly journals CORPORATE BUSINESS VALUATION FOR MERGERS AND ACQUISITIONS

2005 ◽  
Vol 9 (3) ◽  
pp. 173-189 ◽  
Author(s):  
Bioye Tajudeen Aluko ◽  
Abdul-Rasheed Amidu
Keyword(s):  
Mergers And Acquisitions ◽  
Structural Changes ◽  
Fair Value ◽  
Prima Facie ◽  
Clear Understanding ◽  
Exploratory Research ◽  
Real Property ◽  
Business Combinations ◽  
Business Entities ◽  
Corporate Business

Business combinations including mergers and acquisitions are important features of corporate structural changes. The Investments Securities Acts (ISA), 1999 charge the Securities and Exchange Commission with the responsibility to review and approve all business combinations in Nigeria. And, real property is an integral factor in many of such strategic business decisions and, need to be set in a business context. This paper, therefore, examines how corporate business entities are and could be valued for mergers and acquisitions through exploratory research. It also explains the relevance of goodwill, marriage value, and fair value concept in corporate business asset valuation. The paper found out inter‐ alia that the value of holding property to the business needs to be measured against the return that the equity could achieve both within the business and elsewhere. It also, prima facie, shows that the role of the valuer is not one of accountant but interpreter of financial and physical information with a clear understanding of the nature of the business under consideration in merger and acquisition.

Na+ dependence of in vitro pancreatic amylase release

1975 ◽  
Vol 229 (4) ◽  
pp. 1023-1026 ◽  
Author(s):  
JA Williams
Keyword(s):  
Pancreatic Enzyme ◽  
In Vitro Release ◽  
Ionophore A23187 ◽  
Enzyme Release ◽  
Pancreatic Amylase ◽  
Amylase Release ◽  
Stimulus Secretion Coupling ◽  
Vitro Release ◽  
Stimulation Of

The effects of Na+ on the in vitro release of amylase from mouse pancreas were studied. Replacement of Na+ in the medium by Tris, choline, or sucrose blocked the stimulation of amylase release by bethanechol and caerulein, whereas replacement by Li+ was without effect. The inhibiton was rapid and reversible, with stimulated amylase release linearly related to the log of the medium Na+ concentration over the range of 20-100 mM Na+. In contrast to the inhibition of amylase release stimulated by physiological secretagogues, enzyme release stimulated by the Ca2+ ionophore A23187 was unaffected by removal of Na+ from the medium. Tissue and intracellular Na+ and K+ contents were unchanged after stimulation of secretion by physiological stimulants. It is concluded that Na+ may be important in the early steps of stimulus-secretion coupling leading to the putative rise in intracellular Ca2+ that triggers pancreatic enzyme release.

Effects of carbachol on extracellular Na-dependent AIB uptake in rat parotid gland

1980 ◽  
Vol 239 (3) ◽  
pp. G183-G189 ◽  
Author(s):  
G. Keryer ◽  
B. Rossignol
Keyword(s):  
Amino Acid Uptake ◽  
Ionophore A23187 ◽  
Acid Uptake ◽  
Parotid Glands ◽  
Extracellular Medium ◽  
Cholinergic Agonist ◽  
Rat Parotid ◽  
Cholinergic Effect ◽  
Ionophore Monensin

In rat parotid glands the uptake of 2-[1-14C]aminoisobutyric acid (AIB), in vitro, depends on a Na concentration gradient between the intra- and extracellular medium. Ouabain (1 mM) which inhibits the Na+-K+-ATPase and a Na+ ionophore, monensin (which dissipates the Na+ gradient), both suppress this amino acid uptake. Carbachol (5 microM) (through muscarinic receptors) evokes a decrease in AIB uptake, and in the presence of 0.1 mM ouabain the cholinergic effect is enhanced. Ouabain alone (0.1 mM) very slightly depresses the [14C]AIB uptake. Neither 1 microM isoproterenol, nor 1 microM Ca2+ ionophore A23187, which affect the membrane potential in rat parotid acinar cells, modifies the AIB uptake. When the Ca is removed from the incubation medium, carbachol still evokes a small decreasing effect on AIB uptake. From these data we can suggest that the reduced AIB uptake (induced by the cholinergic agonist) appears to be related to a process dependent on variation of intracellular Na concentration that may be triggered by the cholinergic agonist.

Spontaneous injury in isolated sheep lungs: role of resident polymorphonuclear leukocytes

1992 ◽  
Vol 72 (6) ◽  
pp. 2475-2481 ◽  
Author(s):  
D. B. Pearse ◽  
J. T. Sylvester
Keyword(s):  
Polymorphonuclear Leukocytes ◽  
Pulmonary Arterial Pressure ◽  
Homologous Blood ◽  
Lung Water ◽  
Histological Techniques ◽  
Pmn Leukocytes ◽  
Pulmonary Arterial ◽  
Pmn Leukocyte ◽  
Leukocyte Concentration

Perfusion of isolated sheep lungs with homologous blood caused pulmonary hypertension and edema that was not altered by depletion of perfusate polymorphonuclear (PMN) leukocytes (D. B. Pearse et al., J. Appl. Physiol. 66: 1287–1296, 1989). The purpose of this study was to evaluate the role of resident PMN leukocytes in this injury. First, we quantified the content and activation of lung PMN leukocytes before and during perfusion of eight isolated sheep lungs with a constant flow (100 ml.kg-1.min-1) of homologous blood. From measurements of myeloperoxidase (MPO) activity, we estimated that the lungs contained 1.2 x 10(10) PMN leukocytes, which explained why the lung PMN leukocyte content, measured by MPO activity and histological techniques, did not increase significantly with perfusion, despite complete sequestration of 2.0 x 10(9) PMN leukocytes from the perfusate. MPO activities in perfusate and lymph supernatants did not increase during perfusion, suggesting that lung PMN leukocytes were not activated. Second, we perfused lungs from 6 mechlorethamine-treated and 6 hydroxyurea-treated sheep with homologous leukopenic blood and compared them with 11 normal lungs perfused similarly. Despite marked reductions in lung PMN leukocyte concentration, there were no differences in pulmonary arterial pressure, lymph flow, or reservoir weight between groups. Extravascular lung water was greater in both groups of leukopenic lungs. These results suggest that resident PMN leukocytes did not contribute to lung injury in this model.

Association of increased pHi with calcium ion release in skeletal muscle

1978 ◽  
Vol 234 (3) ◽  
pp. C110-C114 ◽  
Author(s):  
R. J. Connett
Keyword(s):  
Skeletal Muscle ◽  
Calcium Ion ◽  
Calcium Release ◽  
Muscle Membrane ◽  
Sartorius Muscle ◽  
Ion Release ◽  
Extracellular Medium ◽  
Dantrolene Sodium ◽  
External Potassium ◽  
Frog Sartorius

The pH difference across the cell membrane of frog sartorius muscle cells was measured with the distribution of 5,5-dimethyl-2,4-oxazolidine-dione (DMO) as the marker. Depolarization of the muscles to values at or below the contraction threshold caused by elevating external potassium up to approximately 20 mM resulted in an internal alkalinization. The change was smaller with superthreshold depolarization (20--30 mM [K+]). The alkalinization was blocked by agents that block calcium release from the sarcoplasmic reticulum (procaine and dantrolene sodium). Other agents that cause calcium release (caffeine, theophylline, and quinine) were found to give alkalinization when tested at concentrations just below the contracture threshold. Increased acidification of the extracellular medium was associated with the internal alkalinization. The data were interpreted as indicating the presence of a calcium-stimulated H+ and/or OH- ion transport system in the muscle membrane.

Sarcolemmal membrane changes related to enzyme release in the imipramine/serotonin experimental animal model.

1976 ◽  
Vol 22 (10) ◽  
pp. 1710-1714 ◽  
Author(s):  
L M Silverman ◽  
H D Gruemer
Keyword(s):  
Animal Model ◽  
Muscular Dystrophy ◽  
Cardiac Tissue ◽  
Enzyme Release ◽  
Sarcolemmal Membrane ◽  
Acid Analog ◽  
Amino Acid Analog ◽  
Membrane Changes ◽  
Genetically Determined ◽  
First Time

Abstract We report specific findings in the imipramine/serotonin animal model that are consistent with sarcolemmal membrane alterations. Among these findings are cytoplasmic enzyme release, diminished uptake of alpha-aminoisobutyrate (an amino acid analog), decreased oxygen consumption in isolated rat diaphragm, and ribosuria. Furthermore, we describe for the first time the release of the MB isoenzyme of creatine kinase from a source other than cardiac tissue; that is, isolated diaphragms from imipramine/serotonin-treated animals release increased amounts of MB isoenzyme as compared to diaphragms from control animals. We believe the similarities between this animal model and the human disease (Duchenne muscular dystrophy) support a genetically determined generalized membrane abnormality in the pathogenesis of this form of muscular dystrophy.

scholarly journals Changes in ionic movements across rabbit polymorphonuclear leukocyte membranes during lysosomal enzyme release. Possible ionic basis for lysosomal enzyme release.

1977 ◽  
Vol 75 (3) ◽  
pp. 635-649 ◽  
Author(s):  
P H Naccache ◽  
H J Showell ◽  
E L Becker ◽  
R I Sha'afi
Keyword(s):  
Lysosomal Enzyme ◽  
Polymorphonuclear Leukocytes ◽  
Cytochalasin B ◽  
Calcium Influx ◽  
Flow Diagram ◽  
Ionophore A23187 ◽  
Enzyme Release ◽  
45Ca Efflux ◽  
Ionic Movements ◽  
Ionic Basis

Changes in the movements of Na+, K+, and Ca+2 across rabbit neutrophils under conditions of lysosomal enzyme release have been studied. We have found that in the presence of cytochalasin B, the chemotactic factor formyl methionyl leucyl phenylalanine (FMLP) induces within 30 s large enhancements in the influxes of both 22Na+ and 45Ca+2 and an increase in the cellular pool of exchangeable calcium. The magnitude of the changes induced by cytochalasin B and FMLP exceeds that induced by FMLP or cytochalasin B alone, and cannot be explained on the basis of an additive effect of the two agents. However, these compounds either separately or together produce much smaller enhancements in 45Ca efflux. The divalent cation ionophore A23187 also produces a rapid and large increase in the influxes of both 22Na and 45Ca+2 in the presence and absence of cytochalasin B. We have also found an excellent correlation between calcium influx and lysosomal enzyme release. 42K influx is not significantly affected by any of these compounds. On the other hand, a large and rapid increase of 42K efflux is observed under conditions which give rise to lysosomal enzyme release. A flow diagram of the events that are thought to accompany the stimulation of polymorphonuclear leukocytes (PMNs) by chemotactic or degranulating stimuli is presented.

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