scholarly journals Arrest of membrane fusion events in mast cells by quick-freezing.

1980 ◽  
Vol 86 (2) ◽  
pp. 666-674 ◽  
Author(s):  
D E Chandler ◽  
J E Heuser
Keyword(s):  
Plasma Membrane ◽  
Mast Cells ◽  
Membrane Fusion ◽  
Extracellular Space ◽  
Freeze Fracture ◽  
Secretory Process ◽  
Membrane Pores ◽  
Peritoneal Mast Cells ◽  
Quick Freezing ◽  
Rat Peritoneal Mast Cells

We have used quick-freezing and freeze-fracture to study early stages of exocytosis in rat peritoneal mast cells. Mast cells briefly stimulated with 48/80 (a synthetic polycation and well-known histamine-releasing agent) at 22 degrees C displayed single, narrow-necked pores (some as small as 0.05 micrometer in diameter) joining single granules with the plasma membrane. Pores that had become as large as 0.1 micrometer in diameter were clearly etchable and thus represented aqueous channels connecting the granule interior with the extracellular space. Granules exhibiting pores usually did not have wide areas of contact with the plasma membrane, and clearings of intramembrane particles, seen in chemically fixed mast cells undergoing exocytosis, were not present on either plasma or granule membranes. Fusion of interior granules later in the secretory process also appeared to involve pores; granules were often joined by one pore or a group of 2-4 pores. Also found were groups of extremely small, etchable pores on granule membranes that may represent the earliest aqueous communication between fusing granules.

scholarly journals Olopatadine Inhibits Exocytosis in Rat Peritoneal Mast Cells by Counteracting Membrane Surface Deformation

2015 ◽  
Vol 35 (1) ◽  
pp. 386-396 ◽  
Author(s):  
Asuka Baba ◽  
Masahiro Tachi ◽  
Yoshio Maruyama ◽  
Itsuro Kazama
Keyword(s):  
Plasma Membrane ◽  
Mast Cells ◽  
Lipid Bilayers ◽  
Surface Deformation ◽  
Lucifer Yellow ◽  
Membrane Surface ◽  
Water Soluble ◽  
Confocal Imaging ◽  
Peritoneal Mast Cells ◽  
Rat Peritoneal Mast Cells

Backgroud/Aims: Besides its anti-allergic properties as a histamine receptor antagonist, olopatadine stabilizes mast cells by inhibiting the release of chemokines. Since olopatadine bears amphiphilic features and is preferentially partitioned into the lipid bilayers of the plasma membrane, it would induce some morphological changes in mast cells and thus affect the process of exocytosis. Methods: Employing the standard patch-clamp whole-cell recording technique, we examined the effects of olopatadine and other anti-allergic drugs on the membrane capacitance (Cm) in rat peritoneal mast cells during exocytosis. Using confocal imaging of a water-soluble fluorescent dye, lucifer yellow, we also examined their effects on the deformation of the plasma membrane. Results: Low concentrations of olopatadine (1 or 10 µM) did not significantly affect the GTP-γ-S-induced increase in the Cm. However, 100 µM and 1 mM olopatadine almost totally suppressed the increase in the Cm. Additionally, these doses completely washed out the trapping of the dye on the cell surface, indicating that olopatadine counteracted the membrane surface deformation induced by exocytosis. As shown by electron microscopy, olopatadine generated inward membrane bending in mast cells. Conclusion: This study provides electrophysiological evidence for the first time that olopatadine dose-dependently inhibits the process of exocytosis in rat peritoneal mast cells. Such mast cell stabilizing properties of olopatadine may be attributed to its counteracting effects on the plasma membrane deformation in degranulating mast cells.

Clarithromycin Dose-Dependently Stabilizes Rat Peritoneal Mast Cells

Chemotherapy ◽  
2016 ◽  
Vol 61 (6) ◽  
pp. 295-303 ◽  
Author(s):  
Itsuro Kazama ◽  
Kazutomo Saito ◽  
Asuka Baba ◽  
Tomohiro Mori ◽  
Nozomu Abe ◽  
...  
Keyword(s):  
Mast Cell ◽  
Plasma Membrane ◽  
Mast Cells ◽  
Water Soluble ◽  
Patch Clamp Technique ◽  
Membrane Deformation ◽  
Whole Cell Patch Clamp ◽  
Peritoneal Mast Cells ◽  
Rat Peritoneal Mast Cells ◽  
First Time

Background: Macrolides, such as clarithromycin, have antiallergic properties. Since exocytosis in mast cells is detected electrophysiologically via changes in membrane capacitance (Cm), the absence of such changes due to the drug indicates its mast cell-stabilizing effect. Methods: Employing the whole-cell patch clamp technique in rat peritoneal mast cells, we examined the effects of clarithromycin on Cm during exocytosis. Using a water-soluble fluorescent dye, we also examined its effect on deformation of the plasma membrane. Results: Clarithromycin (10 and 100 μM) significantly inhibited degranulation from mast cells and almost totally suppressed the GTP-γ-S-induced increase in Cm. It washed out the trapping of the dye on the surface of mast cells. Conclusions: This study provides for the first time electrophysiological evidence that clarithromycin dose-dependently inhibits the process of exocytosis. The mast cell-stabilizing action of clarithromycin may be attributable to its counteractive effect on plasma membrane deformation induced by exocytosis.

scholarly journals Molecular events during membrane fusion. A study of exocytosis in rat peritoneal mast cells.

1977 ◽  
Vol 72 (2) ◽  
pp. 242-259 ◽  
Author(s):  
D Lawson ◽  
M C Raff ◽  
B Gomperts ◽  
C Fewtrell ◽  
N B Gilula
Keyword(s):  
Mast Cells ◽  
Membrane Proteins ◽  
Lipid Bilayers ◽  
Freeze Fracture ◽  
Intramembrane Particles ◽  
Molecular Events ◽  
Peritoneal Mast Cells ◽  
Granule Membrane ◽  
Rat Peritoneal Mast Cells ◽  
Membrane Changes

We have used thin section and freeze-fracture electron microscopy to study membrane changes occurring during exocytosis in rat peritoneal mast cells. By labeling degranulating mast cells with ferritin-conjugated lectins and anti-immunoglobulin antibodies, we demonstrate that these ligands do not bind to areas of plasma membrane or granule membrane which have fused with, or are interacting with, granule membrane. Moreover, intramembrane particles are also largely absent from both protoplasmic and external fracture faces of plasma and granule membranes in regions where these membranes appear to be interacting. Both the externally applied ligands and intramembrane particles are sometimes concentrated at the edges of fusion sites. The results indicate that membrane proteins are displaced laterally into adjacent membrane regions before the fusion process and that fusion occurs between protein-depleted lipid bilayers. The finding of protein-depleted blebs in regions of plasma and granule membrane interaction raises the interesting possibility that blebbing may be a process for exposing the granule contents to the extracellular space and for the elimination of excess lipid while conserving membrane proteins.

scholarly journals Native heparin from rat peritoneal mast cells.

1977 ◽  
Vol 252 (2) ◽  
pp. 518-521 ◽  
Author(s):  
R W Yurt ◽  
R W Leid ◽  
K F Austen
Keyword(s):  
Mast Cells ◽  
Peritoneal Mast Cells ◽  
Rat Peritoneal Mast Cells
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